Valve is releasing more and more of their games for the Linux platform. Latest available betas are Half-Life 2, HL2:Episode One, HL2:Episode2 and Left 4 Dead 2.
So everyone who likes Gordon Freeman is invited to pick up the crowbar again.
Valve also implemented support for the Oculus Rift in HL2. So you could have an experimental virtual reality experience if you are one of the Oculus Rift beta testers.