I think the whole point is, if it's a GLOBAL define then you'll have to compile it all anyway to make sure a variable isn't defined as something else
separate your defines into sections like global.txt, ego.txt, act1.txt, act2.txt, island.txt, debug.txt, intro.txt, endgame.txt, door.txt
depending on how your game is laid out. For logic in certain sections of a game, just include act1.txt or something like that. If you want to use some door code, include door.txt. Only put in real global definitions into global.txt (ie, the system vars/flags)
That way, if you change or add a variable to just the intro section.. you'll only have to recompile all the logics that have included intro.txt
- Nick