Counter Strike Global Offensive
Today's update includes two maps (de_vertigo and ar_monastery), a wide range of fixes, and an overhaul of the matchmaking for the Classic Competitive mode.
CS: GO features new maps, characters, and weapons and delivers updated versions of the classic CS content (de_dust, etc.).
If you are stealthy enough, you can stab your knife in the enemy's back. Play against real players for best experience.