IV the Revolution

[Edit: This article is a repost after I somehow deleted the original while revising it. My apologies to everyone who commented as those comments have been lost. The Google cache already appears cleared.]

[Edit 2: Now expanded and written up in a PDF]

I'm coming down off the high of Civilisation: Revolution on the iPhone and each hit feels less powerful than the last - so it should only be natural that I turn to it's chemical predecessor, Civilisation IV (Beyond the Sword to be exact) to try to replicate the initial buzz. Playing Civ IV on the weekend was an instructive experience in game design. IV initially feels like an intravenous methodone drip by way of analogy - I spent hours zoned out listening to the classical score, gently clicking the recommended blue options and admiring the graphical upgrade; and then the AI deposits itself on my door step with what Civ players refer to coyly as a 'stack of death' and aiiiieeee the burning and the stabbing.

Rinse and repeat with amusing variations: never figuring out what all this gold I'm accumulating is used for until my units start disappearing with bursts of red text, and then never figuring out how to switch to gold production economy beyond clicking the tiny 'emphasize gold production icons'; starting a religion and having some success spying until an advanced naval stack turns up next to my capital from a country complaining about my sneaky ways and 'wait a sec I never spied on you at all, only my allies'. And so on.

After dropping the difficulty level from Monarch to Prince (I can beat Rev on Deity, how hard can it be?), and experiencing the same feeling of being on a growth curve with less exponents than the AI, I realised it was time to read some strategy guides. They were... instructive. But not so much in how to play the game, but what it is.

This may seem like a truism, but Civilisation IV players like to take micro-management to a whole different level. A level which is obfuscated by the interface. Reading through the numerous guides at Civ Fanatics, the strategies described feel like breaking the game. Switching to a slave economy, chopping down forests and rushing units to attack nearby players; micro-managing worker build orders; and so on, none of which appeared important in the ten or fifteen hours I played the game.

And then I started playing Civilisation Revolution using some of the strategies suggested for Civ's little brother, and realised how poorly I had been playing. Walking through the steps required to horse rush from an American start showed how I should be winning in 1000 BC on Deity, instead of 19XX AD. And the impact of the start conditions becomes much more obvious: having the last enemy Civ over water adds another 1000 years or so to the conquest timeline.

In both instances, the starting and default suggestions are less than optimal, and I had been playing through multi-hour long games without realising the serious errors I had been making in turns 1-10. Then there's the differences between single player and multi player: in both flavours of Civilisation, the AI plays nothing like human players, and so little of the skills learned in one flavour of the game are transferable - in fact many will ruin the game experience for you and other players.

In a classic strategy game like Starcraft, there is a delicate and interesting balance between rushing - where you spawn lots of small cheap units and attempt to overwhelm the other players; booming - where you attempt to climb up the tech up the tree, possibly through building a second expansion; and turtling - where you build up defenses in preparation for an early rush.

Both Civilisation user interfaces emphasize booming - actively asking you to choose which tech you want, and what buildings or units you need to build. Revolution improves on IV by at least defaulting to producing warrior units, and will continue to produce military units if you select to produce one. And the target audience seems to be at a casual level people who like the feeling of building up a huge delicately balanced empire. Then there's this grand tradition in multi-player in both turn based and RTS games of people setting house rules to prevent rushing, which misses the point of this strategy balance. If no one rushes, everyone booms because the turtling leg of this rock, paper, scissors solution is not worth investing in. If you're all booming, random start conditions and tiny mistakes get infinitely magnified, so that the game ends up being about which player can pull a slot machine the fastest or most accurately.

But reading through the Civilisation forums, the majority of strategies involve rushing - because booming and turtling strategies are ineffective at the highest level. More casual players only booming encourages dedication to this rush strategy for more competitive players. A big part of the problem is that it is too easy to boom while you're rushing: you steal geographical space over the map which then lets you build anywhere. Starcraft avoids this problem by geographically concentrating the resources required to build expansions in a few discrete areas instead of all over the map.

My dissatisfaction with Civilisation IV is at heart because the optimal strategies are so divorced from the way the game feels like it 'should' be played. Civilisation Revolution at least gets this mostly right - but it fails at the hurdle of making boom and turtle strategies more viable. Every strategy guide I've seen is rush, rush, rush.

The remainder of this post is going to be me engaging in my usual 're-design the game post-analysis'. I couldn't resist what amounts to intellectual masturbation, but that's how I'm programmed. So below are my Civilisation Revolution house rules - I'd love to be able to implement and test them, preferrably as a Civilisation IV mod, but that'll be a lot of work.

I've gone through several iterations of how I'd modify the game, and it's been a useful exercise for me when I eventually write my own technology tree based game. The first lesson is that expanding the tech tree itself has been a major design failure - so what you see here is based entirely on the existing Civ Rev tech tree. The Civilization IV tech tree throws too many tech choices at you far too early, with them only having minimal impact on your immediate game play. The Civ Rev tech tree feels about right in it's frequency and spread of tech choices: if almost a little too tech rich in the late game, but that could equally be the fact I've been playing like a boom player.

I've also thrown out all my early unit design additions - again you'll not see any additional units suggested here. I've done this after initially underrating horsemen, and then seeing virtually every strategy starting with a horse rush, excluding those civs which have an overpowered warrior unit. So if I couldn't get the unit balance right to start with, there's no point me suggesting anything that may completely blow the balance out of the water. (One significant issue I have is that tanks feel like they appear far too early - there's none of the uncomfortable drawn out trench warfare that characterised the First World War. I've tried to tune this a little with the Foundry building).

Similarly I've not created any new wonders - there's enough already.

I've borrowed one suggestion from the Civ Rev forums, by developing a set of economic, religious, philosophy and military doctrine civics. These are chosen the same way as governments, and cause anarchy when you change. In particular I can't overemphasise how much I want to explore non-traditional economic models of society development. I've tried to enumerate most of them here: in particular the cottage or free market economic model that was responsible for much of the early liberalisation in China in the last fifteen years before it was railroaded into oligopolistic state run economy. The one economic model I've missed out in the civics is the trading model which developed between settled agrarian societies and hunter/gatherer tribes which existed for so long in prehistory and was responsible for much early development.

Government Civics
Just 2 changes to governent civics: Despotism adds an ability and Democracy replaces the existing Democracy effect. I've included the remaining civics for completeness.

Despotism (from start)
You may change your economy without revolution. No loss of culture after firing a nuke.

Monarchy (requires Monarchy)
Doubles the culture bonus from the Palace.

Republic (requires Code of Laws)
Settlers cost just 1 population point.

Communism (requires Communism)
+50% production in cities. Temples and Cathedrals do not produce culture.

Democracy (requires Democracy)
You may change your philosophy without revolution. Units without Loyalty get +50% defense in home territory.

Fundamentalism (requires Religion)
All units get +1 to attack. Libraries and Universities do not produce research.

Economic Civics

Gift Culture (from start)
Give gold to other nations in return for culture. That nation only receives a taxable share of the gold at the start of their next turn and the remainder turns into culture for you. (e.g. you 'gift' 100 gold. The recipient gets 30 gold at the start of their next turn. You get 70 culture).

Slavery (requires Bronze working)
Sacrifice population to rush production early. e.g. you can rush at any time. If you don't have enough production stockpiled to do so normally, your city loses one population.

Bureaucracy (requires Literacy)
Palace doubles city worker output of your capital instead of culture bonus (Bureaucratic monarchies get the non-monarchy palace culture bonus) - the city worker output is the +1 production, +X trade you get from working the city square.

Vassalage (requires Feudalism)
Plains and grasslands generate +1 trade if they contain your military units (spies, caravans and explorers don't count).

Cottage Industry (requires Printing Press)
Plains and grasslands generate +1 production.

Oligarchy (requires the Corporation)
+50% gold production from cities. You do not get the benefit of resources.

Capitalism (requires Globalization)
Double the benefit of resources.

Religious civics

Paganism (from start)
Barbarians can be friendly (All other religious civics only receive 15 gold from sacking friendly barbarian villages - never any other bonus).

Ancestor Worship (Ceremonial Burial)
Your units being killed generates culture (equal to their production cost times a multiplier based on period: ancient 90%, medieval 80%, industrial 70%, modern 60%).

Polytheism (Writing)
Libraries generate culture. Cathedrals have no effect.

Monotheism (Religion)
Temples generate gold. Banks have no effect.

Theocracy (Code of Laws)
Temples also act like Barracks. Cathedrals also act like Academies. Libraries and universities are destroyed when you capture a city.

Atheism (Communism)
Temples and cathedrals not destroyed when you capture a city.

Philosophy Civics

Superstitious (from start)
Your cities cannot be captured if they have at least one building. You cannot choose to become Superstitious again once you adopt another Philosophy civic.

Open (requires Alphabet)
Other civilisation units may move through your territory without being at war with you. Each turn, you automatically trade one technology with a civilisation you have met and are not at war with, unless that civilisation already controls all the technologies you have. Each side randomly picks a technology the other does not have, and gives it to them.

Spiritual (requires Irrigation)
You may change your religion without revolution. Instead of culture flipping, your cities pay tribute when they fall under the influence of another civilisation; they fall under the influence more easily than culture flipping.

Expansionist (requires Railroad)
Your units get +1 movement.

Rational (requires Mathematics)
+50% research in cities. Cathedrals and Banks have no effect.

Industrious (requires Industrialization)
+33% production. Universities have no effect.

Pacifist (requires Printing Press)
+50% city growth. You may not declare war or refuse surrender.

Military Doctrine Civics

Raiding (from start)
Your units do not cost gold to maintain. Other military doctrines require 10% of the production cost of your units to maintain them at the end of your turn. If you cannot pay the maintenance costs, you automatically suffer anarchy and switch to the Raiding military doctrine at the end of the period of anarchy.

Militia (requires Code of Laws)
Your undefended cities sacrifice one population to be defended by a militia with strength equivalent to the current defensive unit (warrior, phalanx, rifleman, infantry or modern infantry) when attacked the first time during your opponent's turn. Militias do not attain veterancy or promotions and are disbanded at the start of your turn, before paying for upkeep.

Resistance (requires Monarchy)
New units get a free promotion. Existing units get a free promotion when you change to the Resistance civic. Units outside your home territory lose a random promotion at the end of each turn. When you change away from the Resistance civic, all your units lose a random promotion (but not veterancy).

Propaganda (requires Printing Press)
Barracks and foundries produce armies/fleets/wings instead of individual units. Academies, docks and high-tech labs have no effect.

Conscription (requires Communism)
Your armies consist of four units instead of three, and have four times the attacking and defensive strength.

Professional (requires The Corporation)
You can promote a military unit once per turn by paying gold equivalent to its production cost, up to a maximum of three promotions.

The biggest problem with Civilisation is that there is no balance against having too many cities, beyond some early expansion costs when the population cost of settlers is high compared to the starting city population. I believe that there should be two balancing factors: firstly, for every 3 cities you have, you should have to acquire one additional technology to advance an technology age (e.g. from Ancient to Medieval). Secondly, and more interestingly, the number of cities you control should impact the amount of anarchy you suffer.

Anarchy

You must suffer anarchy whenever you want to change any civic which you cannot change for free. You only suffer anarchy if you control more than one city - civilisations with one city may choose to change any of their civics for free. When you learn a technology which gives you access to a civic, you may adopt one civic which that technology makes available without suffering anarchy. You can only choose one, if a technology makes multiple civics available.

You may choose from the following types of anarchy:

Disaster (from start; lasts 1 turn)
A random city except your capital has a building or wonder destroyed or great person killed - for every two cities you control - ignore cities you gain tribute from or have installed puppets in. If all buildings and wonders are destroyed and great people are killed, one population is sacrificed instead for each remaining two cities not accounted for. It is possible to have a city destroyed this way. You choose which civic to adopt the following turn.

Unrest (requires Alphabet; lasts 1 turn for every two cities you control)
Your cities produce no output including those cities you have installed a puppet in. Civilisations which do not have city production affected by anarchy only do so for the first turn of unrest - subsequent turns do affect them. You choose which civic to adopt at the end of the unrest.

Plague (requires Pottery; lasts 1 turn for every 2 cities you control)
All your cities sacrifice one population per turn down to the minimum city size for the era - ignore cities you gain tribute from or have installed puppets in. You choose which civic to adopt at the end of the plague.

Pogrom (requires Writing; lasts 1 turn)
All your cities sacrifice one population for every two cities you control down to the minimum city size for the era - ignore cities you gain tribute from or have installed puppets in. You choose which civic to adopt the following turn.

Inquisition (requires Religion; lasts 1 turn for every two cities you control)
Your cities produce no science and you receive no science tribute. In addition, all your cities lose one population the first turn of the inquisition if they have more than the minimum city size for the era - ignore cities which you receive tribute from or have installed puppets in. You choose which civic to adopt at the end of the inquisition.

Revolution (requires Monarchy; lasts 1 turn for every two cities you control)
Your cities produce no wealth and you receive no wealth tribute. In addition, all your cities lose one population the first turn of the revolution down to the minimum city size for the era - ignore cities you gain tribute from or have installed puppets in - and the size of your treasury halves at the first turn of the revolution. You choose which civic to adopt at the end of the revolution.

Civil War (requires Democracy; lasts 1 turn)
You lose control of half of your cities. Control of your cities is given to a civilisation not currently in the game and controlled by an AI. The cities are split up geographically, and you choose which side to take. All the technologies you have learned are given to the recipient of the remaining cities, along with any units in those cities and that civilisation starts with the civics you had prior to changing. You choose which civic to adopt the following turn.

Coup (requires Communism; lasts 1 turn for every two cities you control)
Your units may not move. Any units in your capital are destroyed the first turn of the coup - if you have none, a random military unit is destroyed. You can choose which civic to adopt at the end of the Coup.

Fiat (requires you are currently Despotism)
Fiats are issued by Despots. You can choose which Economic civic to adopt the following turn without penalty.

Election (requires you are currently Democratic)
Elections are held by Democracies. You can choose which Philosophy civic to adopt the following turn without penalty.

Enlightenment (requires you are currently Spiritual)
Enlightenment is gained by Spiritual nations. You can choose which Religious civic to adopt the following turn without penalty.

One issue with Civilisation IV is that the loss of a city is too much of a set back in the early game. To try to slow things down, I added the default superstitious philosophy civic which prevents very early city captures. Ironically, I had spent some time working on this prior to reading that Civilisation V city capture rules - where you install a puppet ruler to get partial control over a city. The capture rules as codified here have demand tribute equivalent to the Civ V puppetry rules, and install puppet the reverse. By splitting revenue down the middle, both sides have an incentive to defend the city against a third attacker.

Capturing Cities

When you would normally capture a city, you are instead given several choices:

Capture City (from start, not permitted if your opponent is superstitious or you are receiving tribute from this city)
You take control of the city. Temples and Cathedrals are destroyed unless you have the Atheism civic; Libraries and Universities are destroyed if you have the Theocracy civic.

Pillage (requires Horseback riding, not permitted if you are receiving tribute from this city or have already pillaged it this turn)
You destroy a random building (except the palace), wonder or kill a great person and any accumulated production. The attacking unit returns to your palace (or a random city) and you get gold equal to 80% of the destroyed value.

Demand Tribute (requires Code of Laws)
You receive 50% of the wealth and research output of the city from the next turn onwards, but cannot capture, pillage or culture flip the city. You lose this if another civilisation captures the city, demands tribute or installs a puppet.

Install Puppet (requires Monarchy)
You take control of the city. The previous owner receives 50% of wealth and research output from the next turn onwards, but cannot capture, pillage or culture flip the city. The previous owner loses this if another civilisation captures the city, demands tribute or installs a puppet.

With Monarchy, Spies may Install Puppet if a city is unoccupied - or perhaps emptied by one or more successful False Orders (see below). The Install Puppet consumes the Spy (as all other spying actions); enemy spies will fight first to determine whether the spying mission is successful.

The other problem which is endemic in the Civilisation series is how to keep players in the game when they begin losing. I want to flatten the tech tree anyway, so that pre-requisites are not as important, and this seems an interesting way to do it.

Managing Setbacks

The prerequisites for some technologies are waived if you perform the following actions - allowing you to potentially leapfrog some required technology if you are doing badly:

Ceremonial Burial: You lose a unit in battle. (Religious).
Ironworking: You find the Iron resource. (No bonus if you already have Ironworking).
Masonry: You have a city pillaged. (Immune to city flipping for one turn).
Writing: A spy steals more 20 or more of your gold, or destroys a fortification which results in you losing a unit in a city the same turn, or kidnaps a Great Person. (Immune to espionage for one turn).
Construction: You lose a naval unit with units on board other than an Explorer (Random unit becomes veteran).
Code of Laws: You have a puppet installed in a city you controlled. (Military Doctrine).
Irrigation: You build a city with no food adjacent to it (Philosophy).
Mathematics: You build a city with no production adjacent to it (Philosophy).
Literacy: You have a city captured. (Military Doctrine).
Democracy: You spend at least 6 turns in anarchy in the game (Government).
Currency: You have tribute demanded of your city. (Economic).
Engineering: You have at least 5 buildings destroyed - by cities being captured, pillaged or spies destroying them (Increased chance of great person for one turn).
Monarchy: You have at least 7 units from civilisations at war with you in your territory or next to cities you control (Government).
Navigation: You circumnavigate the world. (Randomly chosen civic category).
Feudalism: You lose control of your capital city; either by someone capturing it or installing a puppet in it (Military Doctrine).
Banking: A civilisation has 10 more cities than you. (Any at war with you becomes peaceful. No one can declare war on you for 5 turns).
University: You are in the Medieval era when someone reaches the Modern era (Learn one technology for free).
Religion: You have a Settler or Great Person captured without a fight. (Religious).
Invention: You are in the Ancient era when someone reaches the Industrial era (Learn one technology for free).

If you already have the relevant technology, you instead may change the civic (in brackets) without revolution the turn the setback occurs but not subsequently, or otherwise get a temporary bonus if something other than a civic is listed.

You get this benefit only the first time you suffer this setback or perform this action in a game.

One area I have found really rewarding is seeing how much work Civ Rev does with its terrain with so few terrain types available. Hills in particular are a revelation - a simple +1 sight radius and +50% attack as well as defense makes a significant strategic choice in how the game plays. The suggestions I make below attempt to play somewhat on the choices of environmental exploitation versus preservation, with a more subtle mechanic than Civ IV's chop everything in sight. I suspect I'll have to remove the hill quarrying mechanic if only because it makes it too easy to defend locations near hills. I might keep this if only the fact that the world's only triple coned volcano was quarried out of existence in my home town.

Terrain changes

Add three new terrain types: jungle, scrub and wetlands. Jungle is +1 trade, +1 production and gets +1 food with The Corporation (+1 extra with Irrigation for river squares once The Corporation is learned). Scrub is +1 food, +1 production. Wetlands is +1 trade, +1 food (+1 extra food with Irrigation - wetlands are almost always next to rivers). Jungle only occurs within one third of the equator, wetlands only next to coastal or river squares, scrub separates forest and desert.

Settlers can convert some terrain types in return for gold. This takes a full turn and requires that the settler has movement still available. The terrain types are:

Forest to plains for gold with bronze working learned.
Hills to grasslands for gold with masonry learned.
Jungle to grasslands for gold with iron working learned.
Wetlands to plains for gold with engineering learned.
Scrub to grasslands for gold with irrigation learned.

Gold returned is 20 for ancient, 30 for medieval, 40 for industrial and 50 for modern.

Once construction is learned, fortified military units can build a fort in grids other than cities, coastal or ocean terrain at a cost of 25 gold. Forts prevent the attacker from seeing the defensive unit strength unless the attacker is a scout. With engineering, forts also provide +50% defensive bonus. Forts are destroyed when an enemy military unit enters the square.

Units cannot travel over deserts without Horseback riding being learned.

Units cannot attack an enemy location protected by a Fighter except for Forts or Cities, except with Fighters. Balloons and Bombers attacking a Fort or City protected by a Fighter are automatically destroyed.

Many land units can now travel over coastal terrain. They do this by converting into a sea going unit, carrying the land unit, which then moves over coastal terrain only (or ocean terrain with the Ocean going promotion below).

Warriors and Explorers turn into Outriggers (0/1/3).
Settlers, Caravans and Spies turn into Rafts (0/1/2) or Caravels (0/1/3) when Navigation is learned.
Melee and mounted units turn into Barges (0/1/1) or Transports (0/2/4) when Steampowered is learned.
Units with the Amphibious promotion move on water with the same defense and movement statistics as they do on land but cannot attack or provide fire support while on the water. This promotion requires Steel.

Spies may issue False Orders against any city or terrain occupied by an enemy unit. A random adjacent location that the unit may move to is chosen, and the unit moves to it. If the location is already occupied (by either friendly or enemy forces), the Falses Orders fail. The False Orders consumes the Spy (as all other spying actions); enemy spies will fight first to determine whether the spying mission is successful.

Units can only travel horizontally (e.g. east or west only / left or right only) over oceans until Invention is learned.

The last movement peculiarity is of course homage to John Harrison, and in particular by restriction movement in the longitude until he invents the watch necessary to allow it. It's also an attempt to balance out the Atlantis relic a little by making it harder to discover by early navigators.

If I've limited myself to no new units, I've not restricted myself at all when it comes to this next mechanic. Unit promotions - in particular more powerful and interesting promotions - are one of the best features of Civ Rev. I'm sure I've mentioned my love of customising units elsewhere. Well, I want you to be able to go crazy.

I've balanced this, hopefully, by making each promotion require a different technology as a pre-requisite. That way you choices in the technology tree open up what your units are capable of. I'd like to restrict this further by preventing you choose promotions from technology you've acquired through backfilling.

Unit promotions

Units also get experience from naming locations and discovering relics, which can be applied towards upgrades. This allows spies, caravans and explorers to be upgraded as well - which upgrades they can have is listed below.

All unit upgrades require a tech be learned in order to be allowed the promotion. The existing promotions are reproduced below with their requirements.

Blitz - Gains an additional move after attacking; requires Ironworking.
Infiltration - +100% city attack; requires Writing.
Loyalty - +50% defense in home territory; requires Alphabet.
March (Cruise for naval units, Aerodynamics for air units)* - +1 move; requires The Wheel; settlers, explorers, spies and caravans can get this.
Engineering - +100% city defense; requires Engineering.
Guerilla - +50% attack in home territory; requires Code of Laws.
Medic* - unit can heal anywhere; requires Irrigation.
Scout* - unit can see its opponent in city battle and has 1 additional site range; requires Horseback Riding; settlers, explorers, spies and caravans can get this.
Leadership - +100% defense in a stack; requires Literacy.

The following additional promotions are added:

Heroic - +100% defense against same unit type; requires Ceremonial Burial; only pre-gunpowder units can get this.
Irregular: +50% defense against different unit types; requires Gunpowder; only pre-gunpowder units can get this.
Formation: +100% defense against Horsemen and Knights; requires Bronzeworking; only pre-gunpowder units can get this.
Decoy* - Unit appears to be an army/fleet/wing etc. until attacked - only scouts see the real combat strength before combat begins; requires Invention.
Suicide - Unit does one hp damage if it dies; requires Printing Press; only gunpowder units can get this.
Chemical*: Unit ignores fortification and veterancy bonus when attacking; requires Industrialisation; only wheeled units & aerial units can get this.
Incendiary* - Unit promotions do not apply in combat for both attacker and defender when this unit is involved; requires Construction. Veteran bonus and fortifications still apply.
Paratrooper - Unit can be carried in bombers; requires Advanced Flight; only melee units can get this.
Anti-aircraft* - unit can attack aircraft; requires Electricity; only gunpowder units can get this.
Stealth* - not visible on world map unless attacking / defending; only applies to aerial units; submarines are automatically stealthy; requires Superconductor.
ECM* - reveals stealth and decoy units (including submarines) within it's sight range; requires Electronics; only aerial units can get this.
Polar* - Unit can travel over ice; when next to pole treats all other polar locations on same hemisphere as one grid away; requires Atomic Theory; explorers, spies, caravans can get this. Submarines automatically have this when built after Nuclear Power is discovered.
Oceangoing - Unit can travel over coastal and ocean locations; requires Navigation; settlers, explorers, spies and caravans can get this, otherwise warriors but no other unit types.
Mountaineer - Unit can travel through mountains; requires Mathematics; settlers, explorers, spies, caravans and melee units can get this but no other units.
Long Range* - Unit can stay in supply one turn longer. Only aerial units and vehicles can get this. Requires Mass Production.
Pioneer - Unit gets +1 defense and can participate in combat if it normally cannot do so. Settlers, explorers, spies, caravans and melee units can get this but no other units. Requires Pottery.
Amphibious* - Unit can move on water with the same movement statistics that it has on land and can move between land and water squares without stopping - but cannot attack or provide fire support while in the water. Only melee and wheeled units can get this. Requires Steel.
Marine - Unit can attack land from sea without penalty. Only melee units can get this. Requires Steampower.

To complement the promotions, I've added and tweaked some building designs. This way you'll be able to have David building fire boats and running them at the Spanish Armada as well as have something else to spend on in those high production cities other than wonders.

New and modified buildings

Barracks (and cathedrals with theocracy) can now only upgrade melee and mounted units (Horses and Knights).
Trading Post now requires Mathematics instead of Code of Laws.
If a Galley or Galleon is built in a city with a Library, the Explorer unit gets a free promotion.
If a Spy or Caravan is built in a city with a University, the unit gets a free promotion.
If a Settler is built in a city with a Granary, the unit gets a free promotion.
Academy (cost 100): All melee and mounted units get a free promotion. Requires Democracy.
Foundry (cost 100): All wheeled units; naval units; submarine units and aerial units produced in the city will be Veteran. Requires Metallurgy.
Docks (cost 100): All naval units produced in the city get a free promotion (this and Great Leader is the only way naval units be promoted as they do not earn experience in combat). Requires Invention.
Hi-Tech Lab (cost 200): All wheeled units; aerial units produced in the city get a free promotion (this and Great Leader is the only way aerial units be promoted as they do not earn experience in combat); requires Networking. Note only promotions with an asterisk above can be awarded by a Hi-Tech Lab.
Power Plant (cost 150): A city must have a power plant in order to build more than one of Factories, Foundry, Hi-Tech Lab or SDI Defense. Requires Steam power.

Oh what the heck. How about some new units and unit revisions. The revisions are mostly to slow down combat advancement in the later game. I think Civ Rev already has enough units, so this is more an exercise in design balance and fun quirks.

Melee units
Warriors (cost 10, hp 3, combat 1/1, move 1, from start, obsolete with Ironworking)
Legion (cost 10, hp 3, combat 2/1, move 1, requires Ironworking, obsolete with Gunpowder)
Phalanx (cost 10, hp 3, combat 1/2, move 1, requires Bronzeworking, obsolete with Democracy)
Pikemen (cost 15, hp 3, combat 1/3, move 1, requires Democracy, obsolete with Gunpowder)
Riflemen (cost 20, hp 3, combat 3/5, move 1, requires Gunpowder, obsolete with Mass Production and Gunpowder)
Infantry (cost 25, hp 3, combat 3/7, move 1, requires Mass Production and Gunpowder, obsolete with Electronics)
Modern Infantry (cost 30, hp 3, combat 4/8, move 1, requires Electronics and Gunpowder)
Special Forces (cost 40, hp 2, combat 9/3, move 2, requires Communism and Gunpowder. Begins the game with one promotion)

Mounted units
Horsemen (cost 20, hp 2, combat 2/1, move 2, requires Horseback riding, obsolete with Feudalism)
War Elephant (cost 25, hp 2, combat 3/2, move 1, requires Construction, obsolete with Feudalism)
Knights (cost 25, hp 2, combat 4/2, move 2, requires Feudalism, obsolete with Industrialisation and Gunpowder)
Cavalry (cost 30, hp 2, combat 6/2, move 2, requires Industrialisation and Gunpowder, obsolete with Combustion)

Wheeled units
Chariot (cost 20, hp 1, combat 2/1, move 2, requires The Wheel, obsolete with Horseback riding)
Cannon (cost 30, hp 1, combat 6/2, move 1, requires Metallurgy, obsolete with Combustion and either The Automobile or Mass Production, the cannon can choose to bombard indirectly using the siege weapon rules below)
Armoured Car (cost 40, hp 1, combat 6/4, move 3, requires Railroad or Combustion, if without Combustion may only move on roads, obsolete with Mass Production and Combustion)
Tank (cost 50, hp 1, combat 10/6, move 3, requires Mass Production and Combustion)
Machinegun (cost 25, hp 1, combat 2/8, move 1, requires Railroad or Mass Production, if without Railroad may only move on roads, obsolete with Electronics and Gunpowder)

Siege units
These only take damage from aerial units and other siege units when attacking, but can only injure, not kill units except units which started the fight with 1 hp. Unaffected by rivers or walls. Do not move into attacking square.
Archer (cost 10, hp 3, combat 2/1, move 1, requires Bronzeworking, obsolete with Gunpowder)
Catapult (cost 20, hp 1, combat 4/1, move 1, requires Mathematics, obsolete with Metallurgy)
Artillery (cost 40, hp 1, combat 16/2, move 2, requires The Automobile or Railroad, if without The Automobile may only move on roads)

Naval units
Galley (cost 30, hp 1, combat 1/1, move 2, from start; comes with free explorer who gets promotion if galley built in city with a Library, may not move over ocean, obsolete with Construction)
Trireme (cost 30, hp 1, combat 2/2, move 2, requires Construction; comes with free explorer who gets promotion if galley built in city with a Library. May move over ocean but not end up
finishing in ocean squares, obsolete with Navigation)
Galleon (cost 30, hp 1, combat 3/3, move 3, requires Navigation; comes with free explorer who gets promotion if galley built in city with a Library, may move over ocean, obsolete with Steampower)
Cruiser (cost 40, hp 1, combat 6/6, move 5, requires Steam Power, may move over ocean)
Battleship (cost 80, hp 1, combat 12/18, move 4, requires Steel, may move over ocean)
Aircraft Carrier (cost 100, hp 1, combat 4/10, move 4, may move across ocean and can resupply fighters, requires Globalisation)

Submarine units
These are automatically stealthy. It does not cost a move for a submarine to attack.
Submarine (cost 25, hp 1, combat 12/2, move 2, requires Electricity)
Nuclear Sub (cost 80, hp 1, combat 18/3, move 4, requires Nuclear Power)

Aerial units
These are unaffected by rivers, mountains, walls or hills. Cannot capture cities. Can only be attacked by fighters or anti-aircraft units except when in cities or on aircraft carriers (for fighters).
Balloon (cost 20, hp 1, combat 2/2, move 2, requires Invention, obsolete with Flight. Resupply required every 4 rounds)
Fighter (cost 30, hp 1, combat 6/4, move 8, requires Flight. Resupply required every 2 rounds. Resupply permitted from aircraft carrier.)
Bomber (cost 60, hp 1, combat 18/3, move 6, requires Advanced Flight. Resupply required every 4 rounds.)
Rocket (cost 30, hp 1, combat 30/1, move 10, requires Atomic Theory. Rockets require resupply after 1 round. This means if they are not in a city at the end of each turn they are destroyed. Since they cannot capture cities, they are destroyed if they attack).

For convenience, I've included what changes occur for each technology. I've overloaded some and left some unchanged. You may want to compare against the original at Civfanatics.

Technology summary

Advanced Flight: Makes available - Paratrooper promotion.
Alphabet: Makes available - Loyalty promotion; Open Philosophy civic; Unrest anarchy; Explorer unit (built separately for 5 production). Libraries give a promotion to Explorer units if they are built in the same city, either if directly or if attached to a Galley or Galleon. Libraries produce culture with the Polytheism civic. Libraries are destroyed when you capture a city with the Theocracy civic.
Atomic Theory: Makes available - Polar promotion, Rocket unit.
The Automobile: Allows Artillery to move offroad.
Banking: Banks have no effect if Monotheism or Rational civics are chosen. Prerequisites waived if a civilisation has 10 more cities than you.
Bronze Working: Makes available - Slavery civic, Formation promotion, Chop forest, Phalanx unit (in addition to redesigned Archer unit).
Ceremonial Burial: Makes available - Ancestor Worship, Heroic promotion. Temples produce gold if you have the Monotheism civic. Temples are not destroyed if you capture a city with the Atheism civic. Temples also act as Barracks with the Atheism civic. Prerequisites waived if you lose a unit in battle.
Code of Laws: Makes available - Guerilla promotion, Theocracy civic, Militia civic, Demand Tribute city attack. No longer makes Trading Post available (Mathematics is now required). Prerequisites waived if you have a puppet installed by another civilisation in city you controlled. First to reach bonus for Code of Laws allows you to adopt a civic for free without anarchy.
Combustion: Makes available Armoured car unit. Allow Armoured car to move offroad. Required for Tank unit. First to reach bonus replaced by free Armoured car unit.
Communism: Makes available - Atheism civic; Conscription civic; Coup anarchy; Special forces unit (with Gunpowder).
Construction: Makes available - Incendiary promotion; Trireme unit; War Elephant unit. First to reach bonus also includes free Trireme unit. Fortified military units can build a fort in grids other than cities, coastal or ocean terrain for 25 gold. Forts prevent attacking units from seeing defensive unit strength unless the attacker is a scout and are destroyed when an enemy military unit enters the grid. Prerequisites waived if you lose a naval vessel with units in it other than an Explorer.
The Corporation: Modifies jungle: +1 food. Makes available - Oligarchy civic; Professional civic.
Currency: Prerequisites waived if another civilisation demands tribute on a city you control.
Democracy: Makes available - Academy building; Civil War anarchy. Prerequisites waived if you have 6 turns of anarchy this game.
Electricity: Makes available - Anti-aircraft promotion.
Electronics: Makes available - ECM promotion; Modern Infantry unit.
Engineering: Makes available - Engineering promotion, Drain wetlands. Forts provide +50% defensive bonus. Prerequisites waived if you have 5 buildings destroyed - by having cities you control captured, by pillaging, by spies destroying them or by the Disaster anarchy.
Feudalism: Makes available - Vassalage civic. Prerequisites waived if you lose your capital; either by someone capturing it or installing a puppet.
Flight: No change.
Globalization: Makes available - Aircraft Carrier; Capitalism civic.
Gunpowder: Makes available - Irregular promotion. Required for Infantry unit, Modern Infantry unit, Special Forces unit, Cavalry unit.
Horseback Riding: Makes available - Scout promotion, Pillage city attack. Allows movement through Desert. The Oxen resource is now made available by The Wheel. Now requires 30 technology to research.
Industrialisation: Makes available: Industrious philosophy civic, Chemical promotion, Cavalry unit (with Gunpowder).
Invention: Makes available - Docks building, Decoy promotion, Balloon unit. Allows north/south movement over ocean squares. Prerequisites waived if you are in the Ancient era and someone reaches the Industrial era.
Iron Working: Makes available - Blitz promotion. Clear jungle.
Irrigation: Makes available - Medic promotion, Spiritual philosophy civic, Clear scrubland. Prerequisites waived if you build a city with no food adjacent.
Literacy: Makes available - Bureaucracy civic, Leadership promotion. Prerequisites waived if you have a city captured by another civilisation.
Masonry: Makes available - Quarry hills. Prerequisites waived if you have a city which you control pillaged by another civilisation.
Mass Media: No change.
Mass Production: Makes available - Long range promotion, Infantry unit (with Gunpowder), Tank unit (with Combustion), Machinegun unit. Allows Machinegun unit to move offroad. First to reach bonus replaced by free Machinegun unit, free Infantry unit (if civilisation has Gunpowder) and free Tank unit (if civilisation has Combustion).
Mathematics: Makes available - Rational philosophy civic; Mountaineer promotion; Trading Post. First to reach bonus also includes Free Trading Post. Prerequisites waived if you build a city with no production adjacent.
Metallurgy: Makes available - Foundry building.
Monarchy: Makes available - Resistance civic; Install Puppet city attack; Revolution anarchy. Prerequisites waived if you have 7 units from civilisatons at war with you in your territory or adjacent to cities you control.
Navigation: Makes available - Oceangoing promotion, Caravel seagoing vessel. Prerequisites waived if you circumnavigate the world.
Networking: Makes available - Hi-Tech Lab building.
Nuclear Power: Makes available - Nuclear Sub. Submarines built after Nuclear Power discovered have the Polar promotion.
Pottery: Makes available - Pioneer Promotion; Plague anarchy. Granaries give a promotion to settlers built in the same city.
Printing Press: Makes available - Cottage Industry civic; Pacifist civic; Propagana civic; Suicide promotion.
Railroad: Makes available - Expansionist philosophy civic, Armoured Car unit, Machinegun unit, Artillery unit. The units made available by Railroad may only move on roads or cities until other technologies are learned.
Religion: Makes available - Monotheism religious civic; Inquisition anarchy. Cathedrals have no effect if the Polytheism civic is chosen. Cathedrals give melee and mounted units experience if the Theocracy civic is chosen. Cathedrals are not destroyed if you capture a city with the Atheism civic. Prequisites waived if you have a Settler or Great Person captured or killed.
Space Flight: No change.
Steampower: Makes available - Power Plant building, Transport seagoing vessel, Marine promotion.
Steel: Makes available - Amphibious promotion.
Superconductor: Makes available - Stealth promotion.
University: Universities give a promotion to spies and caravans built in the same city. Universities are destroyed if you capture a city with the Theocracy civic. Universities have no effect if you have the Industrious civic. Prerequisites waived if you are in the Medieval era and someone reaches the Modern era.
The Wheel: The Wheel is a new technology which can be learned from the start and costs 20 to learn. It is the prerequisite for Horse riding. It is required to allow roads to be built and makes available Chariots; March promotion. It enables the Oxen resource be used instead of Horseback riding.
Writing: Makes available - Infiltration promotion, Polytheism civic; Pogrom anarchy. Prerequisites waived if a spy steals 20 or more gold from you, destroys fortifications and you lose a unit from the city in the same turn or kidnaps a Great Person.

If you've made it this far, let me know what you think.