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Last updated October 25, 2026

Action
Shooter

Alien Swarm

Co-operative multiplayer game and complete code base available for free.

Choose an editionStart Party
Choose an editionStart Party
0 playing now

That One Thing

Why Alien Swarm sticks with us

The corridor where the swarm pours in from both ends and your medic is the only reason anyone makes the extraction.

Available editions

3 ways to play Alien Swarm. Each has its own install, community and verification status.

Alien Swarm — Alien Swarm: Reactive Drop edition
Alien Swarm: Reactive DropDefault

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.

GenreActionShooter
FeaturesControllerOnline MultiplayerModsCo-Op
CommunityPlayBound VerifiedvApr 20, 2017
Details
Alien Swarm — Official edition
Official

Co-operative multiplayer game and complete code base available for free.

GenreActionShooter
FeaturesOnline MultiplayerCo-Op
OfficialOfficial
Get the installerDetails
Alien Swarm — Lambda Wars edition
Lambda Wars

A free Source-engine RTS set in the Half-Life universe, playable on Steam.

GenreActionShooter
FeaturesOnline Multiplayer
CommunityPlayBound Verified
Open in SteamDetails

About Alien Swarm

Alien Swarm is Valve's top-down co-op shooter: four marines drop into claustrophobic corridors, burn through ammo, and try not to get overrun by a hive that never stops coming. Classes matter — officer, special weapons, medic, tech — and so does not shooting your teammates when the hallway fills with parasites.

It shipped free on Steam in 2010 as a polished Source engine campaign with bots if friends are scarce. Missions are short, readable, and built around teamwork: cover the tech while they weld, keep the medic alive, and clear nests before the next wave spills out. The campaign is complete; there is no shop gate between you and the ending.

On PlayBound we list the original free Steam build. Controller support is partial on classic Swarm (console exec / Steam Input help); the community continuation Alien Swarm: Reactive Drop is the better pad-first option when you want official full controller support and a still-active multiplayer scene.

Why we picked it

We picked Alien Swarm because it is a finished Valve co-op campaign that costs nothing, plays cleanly in a short evening, and still teaches the same squad habits that later free shooters borrow. It is free gaming with a capital V.

Who it's for

Great if you want

  • +Players who want a short, finished free co-op campaign
  • +Friends who like top-down squad shooters over battle royale
  • +Anyone curious about Valve's free experiments on Source

Look elsewhere if

  • −Players who need modern native full controller support without Steam Input fiddling
  • −Anyone looking for a live service with seasonal content (see Reactive Drop)
  • −Solo players who dislike bots filling empty slots

Features

Singleplayer
Multiplayer
Co-op
Level Editor

Will this run on your PC?

Checking…

System Requirements

Minimum

Windows 7 / Vista / XP · Pentium 4 3.0 GHz · 1 GB RAM (XP) / 2 GB (Vista+) · DX9 GPU 128 MB SM 2.0 · 2.5 GB storage

Recommended

Windows 7+ · Core 2 Duo 2.4 GHz · 2 GB RAM · DX9 GPU SM 3.0 (GeForce 7600 / Radeon X1600 or better) · 2.5 GB storage

Frequently asked questions about Alien Swarm

Is Alien Swarm free?

Yes. Valve released it free on Steam. PlayBound hands off to Steam for download and updates — there is no separate PlayBound-hosted package.

How is this different from Alien Swarm: Reactive Drop?

Alien Swarm is Valve's original 2010 campaign. Reactive Drop is the free community continuation with more content, active multiplayer, and official full controller support. Both are listed separately on PlayBound.

Does it support controllers?

Partially. Classic Swarm often needs Steam Input or console commands. Reactive Drop ships official full controller support.

Can I play offline?

The campaign supports local play with bots. Online co-op needs Steam and a network connection.

Does Alien Swarm have multiplayer?

Yes. Alien Swarm supports up to 4 players. You can host a game on your own PC. PlayBound Connect handles the setup: start a party with your friends, pick how you want to play, and everyone launches into the same game from the PlayBound launcher. It also supports co-op play. There is no subscription and no paid multiplayer tier.

Similar to

Alien Swarm: Reactive DropLeft 4 Dead 2Deep Rock GalacticHelldivers

More Like This

V

Developer

Valve

Valve — from Steam store credits

Released2010
LicenseSee Steam store page
PlatformsWindows
Download size2.0 GB
LaunchInstall
Steam DeckUntested
Official website →

Tags

Free To Play

Alien Swarm controls

Native controller support

This game natively supports a controller — no setup needed.

Default bindings for every input method Alien Swarm supports. These are the game's own defaults — anything you have remapped will differ.

Mouse & keyboard

Default keyboard and mouse bindings.

Movement — Mouse & keyboard
ActionDefault input
MoveW, A, S, D
Combat — Mouse & keyboard
ActionDefault input
Aim / fireMouse / Left Mouse
Secondary fire / meleeRight Mouse
ReloadR
Switch weapons1–4 / Mouse Wheel
Interaction — Mouse & keyboard
ActionDefault input
Use / pick upE
Multiplayer — Mouse & keyboard
ActionDefault input
Marine ordersShift

Verified against the game by PlayBound.

Controller

Default gamepad layout, using the standard face-button names.

Movement — Controller
ActionDefault input
Move / aimLeft / Right Stick
Combat — Controller
ActionDefault input
Fire / secondary fireRight / Left Trigger
Switch weaponY
MeleeRight Bumper
Interaction — Controller
ActionDefault input
Reload / useX / A

Verified against the game by PlayBound.

Community

Official Discord

No verified official Discord has been submitted.

Developers can contact PlayBound to verify an official community link.

PlayBound Discord

Chat with PlayBound players in #alien-swarm.

Join #alien-swarm ↗

Solved this in Discord? Post the fix here so the next player can find it.

Featured in

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Upcoming events

  • 🎉 Alien Swarm Game Night

    2026-11-06 01:00 UTC

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Available editions

3 ways to play Alien Swarm. Each has its own install, community and verification status.

Alien Swarm — Alien Swarm: Reactive Drop edition
Alien Swarm: Reactive DropDefault

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.

GenreActionShooter
FeaturesControllerOnline MultiplayerModsCo-Op
CommunityPlayBound VerifiedvApr 20, 2017
Details
Alien Swarm — Official edition
Official

Co-operative multiplayer game and complete code base available for free.

GenreActionShooter
FeaturesOnline MultiplayerCo-Op
OfficialOfficial
Get the installerDetails
Alien Swarm — Lambda Wars edition
Lambda Wars

A free Source-engine RTS set in the Half-Life universe, playable on Steam.

GenreActionShooter
FeaturesOnline Multiplayer
CommunityPlayBound Verified
Open in SteamDetails

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