Guys!

Alien Swarm: Reactive Drop just got released yesterday!!

Alien Swarm: Reactive Drop extends Alien Swarm, bringing more of everything: maps, aliens, game modes, guns... And most importantly Steam Workshop support.

- Tactical co-op for up to 8 players with a top-down perspective
- Steam Workshop support for community maps and challenges
- New co-operative campaigns
- Challenges: Modifications of the game, just like Mutations in Left 4 Dead 2
- PvP: Deathmatch, Gun Game, Instagib, and Team Deathmatch
- Singleplayer: Play with improved bots on all our official maps
- New Aliens: HL2 antlion guards and more
- New Weapons: Desert Eagle, Devastator, and Combat Rifle, with more to come
- Over 100 Steam achievements
- Leaderboards: compete with your friends for the fastest mission completion
- Improved spectating: see hacking minigames and mouse movements in real time

http://store.steampowered.com/app/563560/