Thanks for the feedback. much appreciated.
I tested the game as much as I could, but only have access to real PAL Amiga's. I'll put a disclaimer on the game page warning about possible NTSC issues.
I know about the code entering issue as it did happen to me once or twice. However, it didn't happen enough for me to be able to track down why. The way to minimize it is to enter the code, leaving at least a second or two between key presses. I'll look into this further.