If you have F.E.A.R. on Steam, the SDK is still available and contains most of the AI code, be careful of licensing issues but it's interesting to study.
Patch the game to 1.08 first.
Then install the F.E.A.R. SDK.
Then find a copy of Visual Studio 2003.
Now, you can even recompile the whole game in Release, Final and Debug mode.
-- JustForFun.
