I do so love the TI-99/4A. I've been going through some TI-99/4A disk archives from the Chicago Texas Instruments User Group (which streams its meetings every month) and one of my favorite finds so far was this fun demo:
https://www.youtube.com/watch?v=ejGlI0yxqGA
Over at https://js99er.net/ there's a fair bit of software available right from the web interface, as well.