Co-operative top-down shooter game available for free. An epic bug hunt featuring a unique blend of co-op play and squad-level tactics.
Recent Reviews:
Very Positive - 89% of the 174 user reviews in the last 30 days are positive.
All Reviews:
Very Positive (7,238) - 93% of the 7,238 user reviews for this game are positive.
Release Date:
Apr 20, 2017

Sign in to add this item to your wishlist, follow it, or mark it as not interested

Play Alien Swarm: Reactive Drop


Recent updates View all (26)

June 26

Alien Swarm: Reactive Drop Update - June 26, 2018

This update brings support for rich presence in both Steam and Discord.

If you participate in Steam Beta you will now see more information in your Friend List window. What map is your friend playing, difficulty, number of slots taken and number of maximum slots available on server, as well as the active Challenge name.

Discord users will see similar information.

Also in Discord players are able to post invites in chats to invite players to join their lobby. As well as using the "Ask to Join" button when clicking on player's nickname.

Feel free to join our Discord community to chat and invite people to play with you.

If you are working on a map you may want to check out the community Source Engine Discord server to gather feedback, share screenshots or invite for playtests. Feel free to share your favorite Discord servers in comments section.

Another major change is we've fixed a bug reported by NoName which was causing game difficulty to become lower after a mission restart. Now mission restart will not lower difficulty. 8-player games on Brutal will become harder. 4-player games are slightly affected too. As this issue was present since Alien Swarm's release we want to hear your feedback to decide whether we keep the change or revert it to how it was before. Please use this discussion to leave your feedback on this issue or create a new discussion if necessary.

  • Added rich presence for Steam and Discord. You need to have Steam Beta installed to see the new features in your friend list window. If you have Discord desktop app installed RD will send an extended status in it. You can also invite people to your lobby using Discord.
  • Added soundscripts required for bonus_mission2 map(thanks to Rock N Roll)
  • Fixed medic rifle has infinite heals with rd_infinite_ammo(thanks to element109)
  • Disabled blinking light at til1MidnightPort. Blinking light at map start was causing frame time fluctuations. Looks like lights with changed appearance are causing frame-time to increase which makes next frame time to be decreased. Such fluctuations in frame-time cause monitor to display the same frame during two monitor refreshes. This results in reduced actual framerate even if game's reported framerate is 60
  • Added rd_suggest_difficulty cvar. If set to 0, game will not show a message suggesting player to change their difficulty(thanks to element109).
  • Added rd_hud_minimap_drawing convar. If set to 0 the player cannot draw on the mini-map and does not receive other's drawings. This does not affect other players ability to draw and receive drawings(thanks to element109).
  • Fixed asw_spawner Skill Level. Brutal and Insane are no longer treated as the same Skill Level.
  • Fixed alien health is being lowered after mission restart. Difficulty modifier was not properly updating, affecting aliens' health(lowering it). Thus asw_adjust_difficulty_by_number_of_marines and rd_increase_difficulty_by_number_of_marines cvars didn't properly work.
16 comments Read more

June 19

Rich Presence: now in Reactive Drop [beta]

Rich Presence is now in the beta branch of Reactive Drop. On the Steam client beta and Discord, more information about the map you are playing will be shown to your friends.
16 comments Read more

About This Game

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

System Requirements

    • OS: Windows® XP or above
    • Processor: Pentium 4 3.0GHz
    • Memory: 2 GB RAM
    • Graphics: DirectX 9 compatible video card with 128 MB, Shader model 2.0. ATI X800, NVidia 6600 or better
    • DirectX: Version 9.0
    • Storage: 4 GB available space
    • Sound Card: DirectX 9.0c compatible sound card
    • OS: Windows® XP or above
    • Processor: Intel core 2 duo 2.4GHz
    • Memory: 4 GB RAM
    • Graphics: DirectX 9 compatible video card with 128 MB, Shader model 2.0. ATI X800, NVidia 6600 or better
    • DirectX: Version 9.0c
    • Network: Broadband Internet connection
    • Storage: 6 GB available space
    • Sound Card: DirectX 9.0c compatible sound card
Customer reviews
High Volume of Reviews Detected:
Exclude  or  View Only
Review Type

Purchase Type


Date Range
To view reviews within a date range, please click and drag a selection on a graph above or click on a specific bar.

Show graph

Display As:
Review Beta NEW!
When enabled, will sort reviews by new Helpfulness score. Read more about it in the blog post.
Show graph
Hide graph
Review Helpfulness Beta Enabled
There are no more reviews that match the filters set above
Adjust the filters above to see other reviews
Loading reviews...