Alien Swarm
Alien Swarm - SDK)
Alien Swarm (2010) is a completely free top-down shoot-em-up for up to four co-op players, which is a remake of the Unreal Tournament 2004 mod with the same name, created by Black Cat Games after the company was bought up by Valve. Its complete source code is provided in a new SDK as a sample project for Source modders, much like 
Team Fortress Classic was for 
GoldSrc.
A mod based on Alien Swarm will not require the purchase of another Valve game to play, but it will not have access to the usual "Source base" HL2 content either.
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.
For mapping in Alien Swarm, see Category:Alien Swarm.
Features
- TileGen
- A new quick-build mapping tool. Level designers create connectible rooms and corridors which can be arranged either by hand or programmatically. TileGen maps can be played in-editor, and/or can be exported to Hammer for further refinement.illuminate an entire scene.
- VTF version 7.5 and PCF version Binary 5 PCF 2
- The latest versions of Source's texture and particle formats.
- Depth of field
- A real-time depth of field shader blurs backdrop scenery.
- Vertex animation
- The ability to animate vertexes directly is now supported.
- Various entity improvements
- Numerous entities have been improved and have new features, such as env_fire and env_projectedtexture.
- Water debris flow
- Water now supports the ability to use a base texture layer that is flowed using a flow map. This implemention is less advanced than
Portal 2's, however. - Lightmap influence on cubemapped materials
- Lightmaps can now tint cubemap reflections in the LightmappedGeneric shader.
- Steamworks integration
- Unclear how useful this will be, as currently Steamworks distribution is required to implement persistence, Steam Cloud, achievements, etc.
SDK and Source Code
The source code for Alien Swarm is included in the Alien Swarm - SDK. It lacks a lot of supporting code that the 
Source SDK provides, however:
The SDK is available to everyone, not just owners of Source games.
Dedicated server
See Alien Swarm Dedicated Server for instructions on setting up your own Alien Swarm dedicated server.
Warning:Uninstalling the Alien Swarm Dedicated Server will uninstall the main game, too!Content
- Alien Swarm (
swarm) - Alien Swarm base (
swarm_base) - Alien Swarm platform (
platform) - Alien Swarm engine branch