Well, there are a number of oldies-but-goodies here that I like to recommend to newcomers.
MDK
Third-person shooter with hilarious over-the-top weapons.
Giants: Citizen Kabuto
First/third-person shooter with squad control and base building elements.
Sacrifice
Third-person fantasy RTS (yes, that is a thing) with great voice acting, story and replayability.
Dungeon Keeper
Base building RTS. Dig out your dungeon, build rooms, summon creatures and show those pesky goody-two-shoes heroes and other keepers who's boss (has nothing to do with the recent shitty pay-to-win android "remake" other than the name).
Star Control 2
A space exploration adventure game with arcade space combat, resource management, RPG elements, tons of alien races and a huge starmap to explore. I'll advise buying the game here to support it, then downloading the free modern source port
The Ur-Quan Masters and play that instead.
All 5 games are characterized by a phenomenal sense of humor.