Evil Genius, a classic "world dominator simulator" produced by Elixir Studios and published by Rebellion, is still beloved by the strategy community.
Originally released in 2004, it joined the ranks of a select few strategy titles that put you in command of the bad guy, like Dungeon Keeper did before it, and Overlord did several years later. It's an oldie but a goodie, and now it's free. With a big catch.
Rebellion is offering the game now through their Rebellion ID system. All you have to do is head here, get a Rebellion account (which understandably could be a dealbreaker), then link your Steam account. Done. That's not really the catch though: Rebellion isn't telling us when this promo ends to create a sense of FOMO.
Here's the official statement: "Since Rebellion’s SO dastardly, they’re not disclosing when the giveaway will end – so players better grab their free copies of Evil Genius quick to avoid delicious, delicious heartbreak!" Dastardly is not the word I'd use, but free is free.
Evil Genius Limited Time Giveaway [Rebellion]