I played Crysis on a Vuzix VR920 in around 2008, that was my first VR other than a virtual boy.
Dual 640x480, frame interleaved 3d at 30hz per eye! if you drop a single frame the eyes got out of sync and switched! I think I had dual 9600GTs at the time and it struggled. I think it also struggled on the dual 9800GTX+ I had after that.
head tracking was purely gyro/accelerometer based and worked very poorly.