This would be epic if someone made a version of Kerbal Space Program that could run on a calculator. Where you could use a (very small) selection of parts to make a rocket, and then launch it, and visit two or three other planets / moons… the game physics could be implemented, too. That would just be awesome. I don't know how to make graphics on the graph screen so I couldn't do it, but I'd imagine someone's up to this challenge. Go as far as you want with it. Try to make it compatible with Ti-83+, but if that's not possible to fit in the RAM size there is DoorsCS7 that can run archived programs, so it can be a bit larger. If still not possible, try to fit it on the Ti-84+, because it has some new functions that the 83 doesn't have. Don't go for color display first, but KSP would be super amazing on a color display too.
With the things you've mentioned, this would probably only work in Assembly(if even). Trying to run it in a regular program with physics and graphics would make it way too slow and not enjoyable.
I found this, but it's for the 84+CSE, not TI-83+.