I'll give this a try in a few minutes in the emulator (by the way, the emulator is located at ftp://ftp.hp.com/pub/calculators/Prime/
and you can use it to make screenshots, but your games will run faster unless you use the WAIT() command).
I made an animated screenshot with Camstudio and VirtualDub:
I like it so far, but I found two issues (although I think one is caused by the emulator?)
-Keys takes a while to register, so to make the snake turn, I have to keep the arrow key pressed for a while, else it won't turn
-If you go backwards, the snake seems to go through itself, as demonstrated in the screenshot above.
What would be cool as new feature would be to add extra colors, such as making the background green and the snake yellow. Perhaps a mode where the field wraps around (so we can go outside the screen and appear on the other) would be nice as well.