(EDIT: the consensus here is that you can do whatever you like but for now you need to open source your engine if you want to join the compo, so just have fun and JAM.)

UDK/Unity/GM are closed source but allowed in the compo.
My homegrown game engine is closed source, too.
I respectfully and flamelessly ask: That’s okay, right?
If I post the pre-compiled binaries publicly but do not share the source?
Peace and love, all.