Just for fun I tried running it via Devhook in emulated 2.71. It worked fine! I'm sure plenty of other people have done this already, but I just figured I'd mention it in case people wanted to know. Exiting brought me back to 2.71 and everything seemed fine.

Great job on this little game, by the way! I'm looking forward to your future releases. This was the first TIFF exploit game I've bothered to try (since I've got a 1.5), but I'm glad I did.

In case you run out of ideas, I have a challenge for you. :-)
Check out the game Spout http://wiki.gp2x.org/wiki/Spout and see if you can remake it as an ASCII game. There's a Windows version available via the main site that is linked from that wiki page. It's a nifty, simple, addictive little game. So it has many of the same qualities of your Invaders game. ;-)