Any RTS game where you can play as the bad guys like Dune, C&C, Warcraft, etc.
Stellaris counts if you take one of the traits that makes you unable to use diplomacy like Fanatical Exterminator or Devouring Swarm.
Call of Chernobyl lets you play as part of the Monolith cult. Every other faction is hostile to you. But hey, at least zombies won't shoot you on sight.
Aliens vs Predator. I guess it's debatable whether or not the xenomorphs are really evil but they're definitely opposed to everything that isn't them.
Does Sacrifice count? I remember that if you sided with Charnel or Pyro you pretty much ended up banishing all the good gods. Sure, you still end up facing off against the asshole who wants to destroy the world instead of rule it, but you're hardly a good person by the end of it. Hell, the story of the protagonist is that he tried to regain control of his kingdom by summoning a demon to destroy the rebels (if I recall correctly). The demon instead destroyed the world, so the protagonist fled across dimensions.