I don't exactly remember off the top of my head, and I'm not at home so I can't check this, but I think you want Break, not Return.
EDIT: Nope, no Break. At any rate, Return is for leaving functions, not just leaving a For loop. Try splitting off that entire bullets loop into a separate function.
Incidentally, I would recommend that anyway to improve modularity and readability. Personally, my main loop just calls a couple functions, with no other code inside. Everything else cascades out from those functions (ie. additional functions called from those functions.)
EDIT: Nope, no Break. At any rate, Return is for leaving functions, not just leaving a For loop. Try splitting off that entire bullets loop into a separate function.
Incidentally, I would recommend that anyway to improve modularity and readability. Personally, my main loop just calls a couple functions, with no other code inside. Everything else cascades out from those functions (ie. additional functions called from those functions.)