Portal 2 engine branch
... 
The 
Portal 2 engine branch was introduced with Portal 2 in 2011. It succeeded the 
Alien Swarm engine branch and was superseded by the 
CS:GO engine branch.
Features
New since the Alien Swarm engine branch is:
- Improved shadow mapping
- The entity
env_projectedtextureis significantly improved. Compared to previous implementations, it has higher default resolution, better edge filtering and support for the caching of shadows from static objects. - Video playback on materials
- Added support to render Bink Video in-game on surfaces.
- Blob particles
- A particle renderer that renders blobs of liquid, used for paint gel in Portal 2.
- World portals
- World portals that can seamlessly link together seperate parts of the world. This feature is exclusive to this engine branch.
- Sound operators
- For defining complex audio behaviour.
- Finished water debris flow
- The base texture water flow feature from the Alien Swarm engine branch has been finished, with flowed normals now distorting color lookup and the flow map's alpha channel controlling color map opacity.
- Better
PS3 Support - Of little use to modders, needless to say! Properly optimized by Valve unlike the PS3 port of
The Orange Box which was done by EA and suffered from occasional frame drops.
Availability
- Portal 2
PUNT
Dino D-Day
INFRA
Tactical Intervention (delisted)
The Stanley Parable
The Beginner's Guide
A third-party, heavily modified version of this engine used for Titanfall & other games by Respawn Entertainment, called the 
Titanfall engine branch, is also available, and it is used on the following games:
- Titanfall (delisted)
Titanfall 2
Apex Legends
Source code for both branches is not available. However, authoring tools exist for custom content.
