Dota 2 engine branch (Source)
(replaced by
)The 
Dota 2 engine branch was introduced in 2013 with the release of Dota 2. It succeeded the Counter-Strike: Global Offensive engine branch, and was the final post-Orange Box Source branch to be made. This branch was quickly succeeded by the release of Dota 2 Reborn update in 2015, which upgraded the game to the then-new Source 2 engine, and made CS:GO branch the latest post-Orange Box Source 1 branch to be available for licensing and maintained until the release of Counter-Strike 2 (which made Portal 2 engine branch the latest post-Orange Box Source 1 branch, alongside the latest Team Fortress 2 branch (derived from Orange Box) that still being maintained with updates). Additionally, this is the only Source 1 engine branch that was never licensed to third-party developers.
It is currently unknown which engine branch was forked for Dota 2, but Portal 2 (running on Portal 2 engine branch), features DotA Camera in Hammer Editor, which likely seems to be included because Valve was developing Dota 2 simultaneously with Portal 2, leading to this feature slipping into Portal 2's engine branch and went unnoticed. This, alongside with the August 2026's Steam2 content leak, given Alien Swarm had only launched few days earlier, a unfinished Dota 2 build from July 26, 2010 was leaked, there was a high chance that the Dota 2 engine branch are most likely forked from Left 4 Dead engine branch.
Features [confirm]
New since the 
CS:GO engine branch is:
- Cloth simulation
- Real-time cloth simulation (i.e. soft-body physics).
- Global lighting
- The world is lit and shadowed dynamically with env_global_light (in addition to pre-compiled light).
- Steamworks integration
- Building upon community-driven features from Team Fortress 2 players will be able to share strategy guides and coach newer players through Steamworks.
- MultiBlend Textures
- 4-way texture blending, upgrading/replacing WorldVertexTransition
- Screen-space Anti-aliasing
- Anti-aliasing for use with deferred shading
- Screen Space Ambient Occlusion
- SSAO post-process shader
- Published demo file format
- Dota 2 Demo Format contains a link and instructions for parsing the Dota 2 demo files
- Custom Addon Support
- See the Dota 2 Workshop Tools for more details.
Availability and usage
Source code and SDK Base for these branches is not available, and this branch was not available for licensing. Additionally, unlike the rest of Source 1 branches, this branch does not have official tools (like Hammer) whatsoever.
