Co-operative multiplayer game and complete code base available for free.
User reviews:
Recent:
Very Positive (292 reviews) - 93% of the 292 user reviews in the last 30 days are positive.
Overall:
Overwhelmingly Positive (14,504 reviews) - 95% of the 14,504 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

    Minimum:
    • 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
    Recommended:
    • 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
Customer reviews
Customer Review system updated! Learn more
Recent:
Very Positive (292 reviews)
Overall:
Overwhelmingly Positive (14,504 reviews)
Recently Posted
YesIAmAKid
1.4 hrs
Posted: August 28
I Originally came here for the Team Fortress 2 Hat, But boy was i amazed, This game is absolutely amazing the story and voice acting was Perfect its Challenging, And requires Effort and Team work, I Played this with one of my Close Friends And we had loads of fun as i was shooting Aliens while he hacked, Definetley going back to this Game, The Graphics are good it Has some horror to it and i liked it

===Pros===
+Challenging
+Good Graphics
+Good Strategy
+The Hacking system was PERFECT
+Every class is important
+There are 2 healers and both are different witch make it unique
+You can be any class with any weapons, Healer with Minigun ETC.
===Cons===
-Aliens all look the Same
-Not much Missions
-Not much options Like Turning off Friendly fire ETC.

This game is Amazing i will surely revisit it with loads of other people, Definitely Worth a Look
9.5/10
Helpful? Yes No Funny
a04coffey
116.1 hrs
Posted: August 27
I played this game back in 2012 with a few of my college room mates and it's so great, we had some great laughs playing together and with increasing difficulty can become extremely stressful (in a good way) trying to handle all the aliens swarming down the halls at you, having to time your reloads together to make sure that there was always a constant stream of bullets/fire/whatever blasting them. I've had countless times on the hardest difficulty where we all fire at the same time, so when we all start reloading, the aliens swarm you in that instant and kill all of you. It's fantastic.
Helpful? Yes No Funny
the bone boss
0.3 hrs
Pre-Release Review
Posted: August 27
i couldnt run it
Helpful? Yes No Funny
$$mlg$$major$$
12.8 hrs
Posted: August 27
do you guys got any 2016 updates
Helpful? Yes No Funny
Jesticles
1.1 hrs
Pre-Release Review
Posted: August 27
Thumbing through the list of games. Written review will come later.
Helpful? Yes No Funny
Crazed Gunman
9.0 hrs
Posted: August 27
The stigma that most "Free" games have means that this game itelf isn't very popular, which is a shame because it should be:

*It helps encourage teamplay
*It's campaign still offers a lot of challenge
*It's one of the best top-down shooters Steam has - at the very low price of, well, free.

There aren't enough people playing this game, and that's the biggest problem the game has.
Helpful? Yes No Funny
83.4 hrs
Posted: August 27
The amount of time i played this game with my friends trying to get all the achievements.
Fun times!
Helpful? Yes No Funny
KrheaKap
1.7 hrs
Posted: August 27
Nice Co-OP with friends but only 1 kampagne but its nice and not easy.
Helpful? Yes No Funny
CosmoHolmes -TPF-
2.7 hrs
Posted: August 27
Super fun game. Playing this with friends was seriously a blast. We are very sad that there were just a few levels. Playing through this game was grreat but shortlived. If alot of levels were added then I wouldn't even mind paying a few bucks for it. Overall I would highly recommend getting 3 friends to play together with, I mean seriously... IT'S FREE WHY WOULDN'T YOU?
Helpful? Yes No Funny
Knifewish
35.2 hrs
Posted: August 26
It's pretty funny game about aliens trying to scratch your space guys. 10/10 scratching cool alieans
Helpful? Yes No Funny
Most Helpful Reviews  In the past 30 days
17 of 22 people (77%) found this review helpful
4 people found this review funny
Recommended
0.2 hrs on record
Posted: August 5
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.
Was this review helpful? Yes No Funny
8 of 8 people (100%) found this review helpful
2 people found this review funny
Recommended
7.0 hrs on record
Posted: August 18
I know one thing , it will never go in game as you and your partner planned in lobby :v
Was this review helpful? Yes No Funny
5 of 5 people (100%) found this review helpful
1 person found this review funny
Recommended
10.4 hrs on record
Posted: August 5
good Co-op game, for LAN parties and such, but a very short story.
Was this review helpful? Yes No Funny
2 of 2 people (100%) found this review helpful
2 of 2 people (100%) found this review helpful
Recommended
0.4 hrs on record
Posted: August 5
This game isn't just free. It's AWESOME and it's free. Bird's eye view alien carnage with attention to detail. Skills (medic/welder/etc) and lots of action. This game is excellent to play with friends considering it can be a hoot to either casual your way through a level or go all in and try your hardest and coordinate as a team. Definitely worth your HDD space.
Was this review helpful? Yes No Funny
3 of 4 people (75%) found this review helpful
3 people found this review funny
Recommended
0.1 hrs on record
Posted: August 3
外国人群では、ゲームソース [SDK] リリースのグループから才能あるデザイナーで弁者の採用からのModです。 無料にてご利用いただけまにゲームの突選手への壮大なバグハン独自にブレンドの [co-op] 戦隊レベルの戦術を確認しました。
Was this review helpful? Yes No Funny
1 of 1 people (100%) found this review helpful
Recommended
9.0 hrs on record
Pre-Release Review
Posted: August 7
Alien Swarm....its hard to believe how long its been since this title was first released. It is a good game, a free game, and a short game. Its essentially a top down shooter (birds eye view), where you kill hordes of aliens as you progress. The campaign is quite short and story is minimalistic at best. Overall however its free with no gimmicks or cash shop, well worth the time to play casually so full recommend.
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1 of 1 people (100%) found this review helpful
Recommended
3.5 hrs on record
Posted: July 31
SUPER FUN! I always have a really fun time when i play this with my friends we play normal and hard mode. ITS SO FUN! There is a reason this game has had overwhelmingly positive reviews on steam. if you havent played this yet play it! though it's a shame that it was abandoned the game could have had more levels, more weapons and more different kinds of aliens :steamsad::steamsad:
Was this review helpful? Yes No Funny
1 of 1 people (100%) found this review helpful
1 person found this review funny
Recommended
20.3 hrs on record
Posted: August 6
best coop played for hours
Was this review helpful? Yes No Funny
1 of 1 people (100%) found this review helpful
Recommended
5.7 hrs on record
Posted: August 6
The game is good. This one thinks it could be scaled back, as it is near impossible to finish alone, and with others it is just as bad. Communication with other Klans is key in this game, but everybody seems to kill♥♥♥♥♥. This one has observed two types of players. There are supports and there are tanks. Neither work alone making the game very difficult, as tanking is never truly valid. One can die from a single parasite, the size of a rock, head humping you to death and you cannot shake it off. And playing as a support this one has realized is impossible alone, as you will run out of ammo very fast and one cannot carry both Med and Ammo crates. This One's final qualm, is that progression is slow. One must Grind alot if they wish to reach the end alone on anything higher than normal.
This one writes it as 9/10 viewing it as an arcade game, and 6/10 as a full game. It is very short and leaves you wanting more.
-1 from Arcade for Replay Value, Near Perfect for what it is. This One thinks it is at the very least sequel worthy.
-4 from Full for Replay Value, Difficulty Scaling, Community, and Fairness as an SP game. One absolutely CANNOT beat this alone. Easy is possible though the jump to normal is huge. Brutal is only possible with a capable, tactical and intelligent squad. It took This One and One Other around 40 minutes to pass the first level on Brutal with half of our deaths being due to FF, so watch your sh*t because we're d*mn good shots and im not just stroking my gooch here.
This one's advice: Take your time, and play it right. Never Pre-load (You lose your clip, Ammo is your life force, your Chi. It would be like using an Eve Syringe before you ran out of Adam in level of value) and Kill Everything that moves before proceeding and fall back to a choke point when it's too much. Never Rush though a level without a Timer. And Watch your fire. Friendly Fire is Brutal in this game and Death is permanent until the level ends or the squad dies. If playing solo, Rock the Ammo Crate & Tech AR for lightning grenades. This game is built to be Iron Manned. One must simply learn to Iron Man it. Float like a Butterfly, and Sting like a Bee. Sure you can play as a class with higher D, Perhaps even use a Ballistic Vest. But in the end, if One is taking damage, One is not dishing out damage, and One will have a hard time killing. If One is not taking damage, One may dish out damage, and One may kill with ease. The key, is to dodge, duck, dip, dive and dodge your way to f*ckthatville because in the end, if you aren't killing them, they're killing you. Focus not on killing the enemy, but on preserving your own life, and that of the team's when online. They eventually stop spawning allowing you to "Train" The enemy as One would in a typical zombie game. However, One is only able to train in large areas, as many Aliens come at once. This One thinks the game's title serves it well in that aspect.
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