I don't want to be spoilsport or anything, but I think it might be best to wait for lazarus to stabilize. It is still pretty problematic and alot of things are still "not working good enough" so adding a branch might be suicidal(they might change something fundamental in LCL design and such)

I understand the idea buy frankly don't see the need for a "game edition" lazarus as it. I'd be happy to have a "distribution" of FPC and Lazarus with most libraries so I don't have to set up lots of headers for C libs.

The only thing "integrated" into Lazarus worthy of effort IMHO is GLScene like things + perhaps a "media player" made with OpenAL or SDL or FMod backend.