There's plenty of games for a TI-83. I got a few myself on here. As for where to get them online? I dunno, check google. Mostly I know people can get them through other people who have them also, if you got a friend who has some on thiers.

But I mostly pass my time in math by programming random stuff on my calculator. Nothing more then simple text based stuff. Makes for interesting effects once I get way into it. Let's just say none of my friends have ever seen a Zero Wing based text story on a calculator before, let alone lasting about 8 minutes worth of text to read. >.>

All programmed in less then a weeks time while learning the code for displaying text and clearing and pausing. Ah good ole times in high school. How little they change for college. >.>

Umm but yeah, google is theb est place to check for that sort of things I would say.