I've been playing Sierra Entertainment and Elixir Studios' Evil Genius and it is very fun, though I haven't managed to get far enough to where it was stimulating. Basically you start off with some money and build a large underground base to conduct your nefarious operations. You recruit minions to come to your base and build. The building system works great, and inside each room you can choose to place objects that correspond to that certain room. For example, in the storeroom you have a briefcase rack, which stores money. In the barracks, you have lockers and bunk beds, in the control room you have control panels, time clocks, memory banks, among others.
You start your international espionage, laundering, and plotting missions from the 'world map,' which basically gives you a breakdown of the nations. The game is very Austin Powers-ish, and the game seems to be placed in the 1970s and 1980s, as it features the Soviet Union. The area is broken up into large regions that all have one common thing (if not more): their defense organization. These larger regions are further broken up into sub-regions where you can assign workers to go and simply hide, plot to do an evil mission such as rescue an imprisoned worker, capture a civilian for interrogation, etc. or steal some of the region's income, which is transferred to you.
So far I am enjoying it and I hope to get more in depth as I continue to play.