Ctrl Alt Ego is new, but is a fantastic immersive sim. If you want pre-2010 though, you’re limited to System Shock 1 and 2, Thief Gold/2: The Metal Age, Hitman: Blood Money, and the original Deus Ex.
Immersive Sims are coming back, but pre-2010 cuts you to essentially the formative classics of the Immersive Sim genre.
If you want to branch out of the strict boundaries of Immersive Sims, Fallout: New Vegas and Vampire: The Masquerade - Bloodlines are both incredible.