I'm wondering from those who played it.

I like the game quite a bit but seems like it's going to take me some time to beat it. I find the game makes me really tired which prevents me from having long sessions. The central mechanic of the game, gravity shifting, turning up to down and left to right, running on ceilings and walls, swinging the camera around, constantly adjusting your visual perception is something I really dig but it's really mentally draining and physically draining on my eye-balls.

I know it might sound weird but I've never had a game make me actually tired like GR2.

Honestly, I can't say it did. It can be a pretty hectic game but on the whole I've never thought of it as being tiring. Then again, It's a 3D game running at 30fps in high contrast environments that requires lots of camera movement. Maybe this is one of those games where you really do need to play in a well-lit room and take 15 minute breaks every hour.