Co-operative multiplayer game and complete code base available for free.
User reviews: Overwhelmingly Positive (12,650 reviews) - 95% of the 12,650 user reviews for this game are positive.
Release Date: Jul 19, 2010

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"(Free) Co-operative multiplayer game and complete code base available for free. Made by Valve."

About This Game

Alien Swarm is a game and Source SDK release from a group of talented designers at Valve who were hired from the Mod community.
Available free of charge, the game thrusts players into an epic bug hunt featuring a unique blend of co-op play and squad-level tactics. With your friends, form a squad of four distinct IAF Marine classes. Plan your attack using an unlockable arsenal of weapons with countless loadout configurations against a wide variety of aliens. Blaze your way through an overrun, off-world colony, eradicating the alien infestation in environments ranging from the icy planet's surface, to a subterranean lava-flooded mining facility.
Along with the game get the complete code base for Alien Swarm that features updates to the Source engine as well as the SDK. Alien Swarm adds 3rd person camera, depth of field, improved dynamic shadows and a wide variety of gameplay additions to the Source engine.
  • Tactical, 4 player co-op action game with a top-down perspective
  • Complete game code and mod tools
  • Unlock persistent items by gaining levels
  • Over 40 weapons and equipment with countless loadout configurations
  • 4 unique classes and 8 unique characters
  • Matchmaking, Steam Cloud, Steam Stats
  • 64 achievements
  • Tile-based map generation tool
  • Powered by Source and Steam

System Requirements

    • OS: Windows® 7 / Vista / Vista64 / XP
    • Processor: Pentium 4 3.0GHz
    • Memory: 1 GB for XP / 2GB for Vista
    • Graphics: DirectX 9 compatible video card with 128 MB, Shader model 2.0. ATI X800, NVidia 6600 or better
    • Hard Drive: At least 2.5 GB of free space
    • Sound: DirectX 9.0c compatible sound card
    • OS: Windows® 7 / Vista / Vista64 / XP
    • Processor: Intel core 2 duo 2.4GHz
    • Memory: 1 GB for XP / 2GB for Vista
    • Graphics: DirectX 9 compatible video card with Shader model 3.0. NVidia 7600, ATI X1600 or better
    • Hard Drive: At least 2.5 GB of free space
    • Sound: DirectX 9.0c compatible sound card
Helpful customer reviews
107 of 115 people (93%) found this review helpful
8 people found this review funny
25.3 hrs on record
Posted: September 4, 2015
-Quick Review-
Alien Swarm is a Top-Down shooter with emphasis on multiplier teamwork with four total players. Alien Swarm was developed by Valve and released mid 2010. Many of the initial players were lured to the game by the lure of an Alien hat you can unlock via an achievement on Alien Swarm.

-Detailed breakdown review-
Story: You are a member of a team of space troopers who are investigating the circumstances of a seemingly abandoned/evacuated space colony, and trying to recover whatever data is still available.

Gameplay: Alien Swarm is played from a top-down shooter angle from a 60 degree camera angle, you move your cursor to aim, and can simultaneously walk any direction using the keyboard keys.
Some people have dedicated servers for Alien swarm, however most people will simply host a game from their computer, your latency will depend on the hosts internet settings and physical location.
As you succeed or fail missions you will gain experience, this experience is put towards your level, when you level you unlock new weapons, armor, and tools. There are 25 potential weapons that can be chosen from, including special weapons like sentry guns.

Achievements: There are 66 achievements on Alien Swarm, after your first level you will get a good grasp of the different achievement difficulties, at the time that I'm writing this review, I've earned 53 achievements, most of which were earned either grinding by myself (by using a console command, it's possible to play solo online), or joining small groups online or playing with a friend occasionally.
There are two types of tough achievements: Beat the game on the hardest difficulties, and speed run achievements, both of these require a fairly coordinated group of players to work together and know what they're doing.

Price: The best part about Alien Swarm is that it's completely free! This is probably because the project was scrapped after the first campaign. It's nice that this game is free, but I would have preferred to pay for the game if it had a single player mode and more campaigns.
The good news is Alien Swarm was released with an “Alien Swarm software development kit” which is also free, so the Steam Community could create their own campaigns! Second best thing to the original dev's picking up the project again.

Conclusion: Story: forgettable, but this game is more about the experience then the story narrative. Gameplay: addicting, fun, best to play with friends. Achievements: Many are soloable, you're better off with a group of pug players the easiest difficulty is your best bet if you want to learn the game. Not an easy 100% completed game. Price: Completely free to play.
I love this game, even if it's free to play. I've enjoyed playing this game in between playing other games more vigorously. I recommend this game to anyone who wants a change of pace from the "status quo" of games out there. "This game will specifically appeal to gamers who enjoy dungeon crawlers, third person shooters, and alien kill grinding.
------Edits and updates------
Edit/Update May 30, 2015:
spelling, grammar, and punctuation fixes, thanks Angfucious! :)
Was this review helpful? Yes No Funny
128 of 158 people (81%) found this review helpful
131 people found this review funny
2,488.8 hrs on record
Posted: September 27, 2015
I hate parasites
I hate buzzers
I hate boomers
I hate harvesters
I hate reds
I hate shieldbugs
I hate rangers
I hate mortarbugs
I hate flamers
I hate Grenade Launchers
I hate frendly fire

I hate this game
But I'm still playing

Was this review helpful? Yes No Funny
38 of 43 people (88%) found this review helpful
10 people found this review funny
23.5 hrs on record
Posted: November 5, 2015
Alien Swarm is proof of Valve's willingness to allow their IP's the experience of rotting to death for their own personal gain via staff resource redistribution. Forget Half-Life 3; if this excellent game could only get a single 15-minute campaign, then there's no more hope for the niche fanbase of Valve's bygone excellence.
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8 of 8 people (100%) found this review helpful
2 people found this review funny
19.9 hrs on record
Posted: October 8, 2015
Alien Swarm is a freeware top-down shooter video game by Valve Corporation. It's a remake of the Alien Swarm mod for Unreal Tournament 2004 and it was developed by the original team, who were hired by Valve during the course of the development process.

A simple, fun and sometimes madly frustrating game. Personally recommended to play as a team of 4. A somewhat steep learning curve but other then that it will hold solid entertainment for a numerous amount of hours.
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6 of 6 people (100%) found this review helpful
9.9 hrs on record
Posted: October 14, 2015
Alien Swarm is a free top-down cooperative shooter where you will have to pass a small campaign of 7 levels of shooting down cute aliens who look like cousins to headcrabs from Half-Life franchise. It's a remake of Unreal Tournament 2004 mod with same name, I sure remember playing that one once.

The thing is, this game is strictly multiplayer. You can't beat it in single-player. Well, I mean, you can surely force yourself to, but it's not designed for this, hard and doesn't reveal full potential. Game has practice mode with bots, but only through the first two levels. Otherwise, you better find three more marines like you. Thankfully, public multiplayer is active enough, can find at least one game running.

And yea, it's focused on teamwork by using loadouts. Got to balance between general and specialization and then not to shoot each other during gameplay. While campaign is short, it grows in difficulty non-stop, so there will be a challenge to a good team. Can always increase difficulty.

It's just a shame that it doesn't fit to lesser player count. I mean, would be nice to have it like in Left 4 Dead, where all spots are always filled with bots and players just take their place, and thus can always expect a support. Because when you play it with just one friend, it's hard to balance between firepower and special stuff. Almost always one tech, almost always one medic or you will die. But hey, not designed for that after all. It sure can be tough with just friend even on easy, sometimes.

Oh, there is no microtransaction. Valve didn't bother to profit from this in anyway, it's just that some devs that Valve hired were original creators of Alien Swarm mod for Unreal, I heard. It got modding support, but no Steam Workshop. And uses leveling system with which you can unlock new items as a way to prolong the life.

But eh. For free, it's pretty nice team game. But could use better music. Like most games.
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