Counter-Strike, one of biggest multiplayer shooters in history and a prime influence for Call of Duty 4: Modern Warfare's online gameplay, is now quite a bit cheaper. Steam's offering the game for 75% off its normal price for the weekend.

The discount brings the game down to $5 from its usual $20. Counter-Strike, which pits terrorists and counter-terrorists against each other in hostage rescue and bomb defusal modes, was originally a free Half-Life mod. Source is the remake that uses Half-Life 2's engine.

The original CS turned ten years old in June. It's amazing how well the gameplay's held up, though.