Counter-Strike: Global Offensive (CS: GO) will expand upon the team-based action gameplay that it pioneered when it was launched 12 years ago. CS: GO features new maps, characters, and weapons and delivers updated versions of the classic CS content (de_dust, etc.).
The steam autumn sale list the game at $3.74.
I went ahead and picked a copy up for myself. If you were on the fence about the game before, this is a cheap buy!