VScript
VScript, introduced in Left 4 Dead 2, is a virtual machine for scripting that acts as an abstract binding layer between the Source engine and external scripts. According to the
Alien Swarm SDK, the following scripting languages are, or could be supported in the near future:
Script files are read from /scripts/vscripts/
inside the game directory.
Implementations
Squirrel
Source Filmmaker
Only exists on the SFM build of TF2. No TF2 or SFM specific API. Unused.
Lua
Portal 2 (Client/UI only)
Python
Scripting Fundamentals
Main article Vscript Fundamentals