I'm a prizm owner, I makes games, hack, and stuff. I'm one of the first owners in the community to own and develop for the Prizm (making some of the very first add-ins for the platform), and am part of the behind-the-scenes hacking team.
My Prizm Games
PrizmCity was my first attempt at a game for the Casio Prizm. It was supposed to be like a SimCity sort of game, but never really turned into anything. Was for a contest, where the mess I had at that point won second place. I don't suggest you actually load it onto your Prizm, but the source might be helpful.
Raptor, a space shooter similar to Phoenix 4.0 for the 84+ series, sporting many enemies, highscores, money system and shops, cool and powerful upgradeable weapons, and more, was my first full Prizm game in C, and one of the first 5 or so add-in games for the platform (and the first shooter!). Released, but still in active further development. Runner-up for the Cemetech Prizm contest.
PONG for beginners was a proof of concept game. I made it to show I could make a full add-in game in under an hour (which I did), provide example code for beginning programmers with C for the Prizm, and to show how small a Prizm game can actually be if coded smartly (this game was under 50KB). No longer needed to be developed, but a recent update I made gave a huge load of commenting for beginners, so check out the source. And of course, it's a fun game.
Rainbow Dash Attack is a game similar to the Robot Unicorn Attack flash game, except with 20% cooler with ponies, and in C for the Prizm! In active development, this game is one of the first to show off software overclocking used in an add-in for the purpose of allowing better graphical effects.
My Prizm Hacking
Pover is a overclocking/underclocking utility, under 30KB, for the Prizm! The Prizm can finally be overclocked, or underclocked, at will! Want to play a game faster? Want to slow down operations to save your battery life a bit? Now you can overclock up to 87MHz, or underclock to as low as 3.6 MHz at the touch of a few keys! A very handy, small utility (under 30KB for the add-in), pick it up today and have even more control over your device! Now updated, so you can change your ICLK CPU clock division ratio to crank a teeny bit more speed out!