aeh.. if you mean by recommend as in "pick 1 out of all those", im gonna have a hard time, i like them all alot 😀
depends what genre, gamestyle you prefer i think
if you are into hardcore puzzle
or fps,
or RPG
platformer
point 'n click
if i had 5 bucks here and now and didnt own any of those games, and liked/loved RPG then i think Witcher 2 on Steams 85% off sale right now would prob be teh biggest bang for the buck atm
but to be honest its hard to pick one over the other since they all are solid in their own field
Worms is hilarious and can be fun multiplay with a friend or such
either Final Doom, HeXen or Wolfenstein 3d are all great fun classic original arcady style FPS
Dark Messiah took a nice spin on RPG by doing it in 1st...