Sorry if re-post, but these games are suppose to be getting Rift support too
Source:
http://www.vorpx.com/games/
Assassins Creed 1+2
Batman Arkham City
Battlefield 3
Bioshock
Bioshock Infinite
Black Mesa Source
Call of Duty Black Ops 1+2
Crysis 1+3
Dead Space
Dear Esther
Deus Ex Human Revolution
Dirt 3 (no head tracking so far)
Dishonored
Dragon Age 1+2
Elder Scrolls: Morrowind (with DX9 mod)
Elder Scrolls: Oblivion
Elder Scrolls: Skyrim
Formula 1 2011 (no head tracking so far)
Fallout 3
Far Cry 1+3
Flight Simulator X
Half Life 2
Mafia 2
Mass Effect 2+3
Metro 2033
Myst V
Need for Speed Most Wanted (no head tracking so far)
Portal
Quake (with DX9 mod)
Race Driver GRID (no head tracking so far)
rFactor
Slender
Splinter Cell 3
STALKER Call of Pripyat
System Shock 2 (with DX9 mod)
Tomb Raider Underworld
Tomb Raider Anniversay
The Witcher