Recs.
Updated
A modern interpretation of the traditional roguelike. Dungeons of Dredmor features plenty of skill trees, quirky humor, and gameplay that has been streamlined to bring the roguelike genre to a new generation of gamers.
SpecsUpdate
Pros
Pro Skill-based class system improves replay value
A character has seven selected skills, which effectively define that character's class: they have access to every skill selected, and no others. The base game contains dozens of skills, with many more available through both mods and official expansions.
Pro Several community mods were bundled as a free official expansion pack
In a testament to the quality of the Dungeons of Dredmor modding community, one official expansion pack consists almost entirely of user-created content. It was released for free, since they're not total capitalist jerks.
Pro Configurable difficulty accommodates both casual and hardcore play
In addition to basic difficulty adjustment, the player can choose whether death is permanent (in classic roguelike style) or merely resets the current level. There is also a mode called "No Time to Grind" where experience points are increased from all sources, but in compensation, levels are smaller.
Pro Genuinely feels different every time
Something with which a lot of games struggle, DoD feels fresh with every replay not only in terms of what happens, but how you go about it and what you see. Rooms actually feel and and look different, which makes for a memorable terrain you want to cling to.
Cons
Con Burden of knowledge
It's not always clear what your stats are for, what your skills do, what skill trees are useful, etc.