Arcanum of Steamworks and Magic Obsceura (Epic free flowing RPG, mostly non-linear, PC)
Dungeon Keeper 2 (Wicked Sim that defies description, PC)
Evil Genius (Slow moving Evil Genius sim, PC)
Starsiege Tribes (GREAT FPS game, sadly obsolete, PC)
Starsiege (Great Mech Battle game, compelling backstory, sadly obsolete, PC)
Kohan II: Kings of War (Unique Strategy game, PC)
Warlords Battlecry 2 (Strategy game with RPG elements, PC)
Majesty The Northern Expansion (Fantasy Kingdom Sim/RTS, PC, Majesty Gold)
Shadowbane (Sadly Obsolete one of a kind MMO, PC)
Romancing Saga: The Minstral Song (Non-Linear RPG, PS2)
SaGa Frontier (Non-Linear RPG, PS1)
Shadows of Amn (RPG, PC)
Fallout 1&2 (Non-Linear Post Nuclear RPG, PC)
Crono Trigger (Fantastic RPG, SNES)
Super Mario RPG (fun colorful Mario RPG, SNES)
Crusader Kings (High Strategy, PC)
Europa Universalis Rome + Vae Victus (High Strategy, PC)
I can think of a lot of others, but those are the first that come to mind.