Dungeons of Dredmor has proven beyond any shadow of a doubt that it is possible to release a commercially successful roguelike in 2011. At the time development on this game started it must have felt like a leap of faith, but the humour and character-filled visual design of the game have proven to be not just a successful gateway drug to other roguelikes, but hugely popular in its own right.
For many hardened roguelike players, Dredmor feels like a roguelike, simplified, and this has proven to be a divisive issue, but that view ignores the smart decisions behind the unique skill system, which encourages you to tweak your character build every time you see the 'Congratulations. You have died.' game over screen. It also ignores the fact that a simpler roguelike is exactly what is needed to bring the pleasures of the genre to a wider audience, and that Dredmor gets the user interface right in a way that many seemingly complicated roguelikes have been unable to do.
And then there is the continued post-release support, and the fact the game is priced so ridiculously low, that make it hard not to recommend you go out and buy it.