Alien Swarm: Reactive Drop

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: Bulldog, 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

Reactive Drop is a standalone Steam release that grew out of Valve's Alien Swarm. It keeps the top-down, squad-based alien shooter and adds new campaigns, new alien types, new weapons, Steam Workshop support for community maps and challenges, leaderboards for the fastest mission completions, and improved bots for solo play.

Because it is its own Steam app (563560) rather than a patch, it installs and updates separately from the original Alien Swarm. PlayBound hands the install to Steam and keeps the page, party tools and controller notes in one place.