So, what other games/engines do you guys mod?

[Gary]

I currently mod the Source engine, which comes with a basic SDK. The SDK comes with "Faceposer" which lets you set up facial animation and Hammer which is what you use to created the levels(brushwork, placing entities, compile lighting). Sadly, the engine does not really work with anything besides brushwork from Hammer for level geometry, lightmaps only work with bsp so you only get vertex lighting on models. It also comes with C++ code for making pretty much anything. Not the most advanced engine, but it's pretty fun to mod.

So, what about you guys?