Basically a Unity3D game. Runs in DirectX 10 and 11 only (no OpenGL or D3D9 compiled). Performance is good and didn't dip below 60 while I played. Only problems are related to mouse movement as in other (older) Unity3D games: Camera/Cursor is drifting slightly when moving the mouse, doors and cut scenes sometimes make the camera go up and/or crazy for a few seconds or until alt-tabbing. Alt-tabbing usually fixes the camera issues except the drifting.