Not sure how many of you are aware of this, but Alien Swarm has been re-released on Steam under the title Alien Swarm: Reactive Drop.
The original game was released 7 years ago and was/is a fantastic top-down co-operative tactical shooter with lots of variety, tense moments and atmosphere.
This new version just adds some extra bits e.g. allowing 8 players to co-operate on each map and Steam Workshop.
If you don't know the game, imagine Starship Troopers or Warhammer 40k's Space Hulk from a top down perspective where players pick different classes, weapons and equ