From Valve Developer Community
VMEX-based map decompiler for the Source engine. It converts BSP format files back into VMF format maps that can be loaded into Hammer. Support has been extended to newer Source engine games, such as Dark Messiah of Might and Magic, Left 4 Dead 2, and Portal 2. Most of the annoying bugs found in the last release of VMEX have been fixed and new features have been added.
New features include:
- Extracting the embedded ZIP file
- BSP analysis
- Support for processing multiple files at once.
- Convenient file Drag 'n' Drop
- Much more!
Decompiling maps may not always result in 100% accurate builds. Some differences (keyvalues, materials, etc.) may not be an exact match as the original map.