I've just started working my way through Prey (PC) at the moment, I like the portals and gravity changes. It would probably be more creepy if I played it for longer at a time but I find it hard to get into the game atmosphere after being at work all day.
Worms 3D (PC) is fun too, I still haven't perfected the Bazooka and Grenades but I'm getting there
Red Steel (Wii) is an interesting game, I'm looking forward to seeing what else they'll be able to cook up for the gun/sword controls in the future. As it is I'm going for 100% accuracy and headshots.