Elidrake

But Chess is a game that you're already familiar with - unless you're going to be changing the absolute foundation of the game with these altered rules, your familiarity with the original game is what allows you to come up with an altered set of rules.

Compare that to Dwarf Fortress, short of 'Sim City' (which is a dubious comparison at best), there is nothing out there that remotely comes close to the myriad of gameplay concepts that have been shoved into this single, mildly coherent package.