I'm working on a port of Undertale to the TI-84 CE, and it's somewhat barren as of now but here is the github repository. Advice is welcome as I'm fairly new to C, let alone programming a calculater lol

https://github.com/slimefolf/calctale

I feel like undertale is a little too much for the ti-84 ce to handle honestly, because of the shaders n stuff, but I think you could make it work

Any screenshots or plans for how you're going to go about making this project?

Another thing to note is that this has technically been done before. Thanks the Github user Undertale-GB, he made a port of Undertale to the Gameboy in full Gameboy code, and through the Ti-boy CE website and TI-boy CE you can turn the file into a playable undertale game on your calc.
Links:
Undertale-GB(source code): https://github.com/Undertale-GB/Undertale-GB/releases/tag/v20
Where the actual TI-84 code is: https://github.com/toxictomb/Undertale-TI-84-plus-CE

And yet it has been done.

seeing that a 3,500 word count fanfiction takes up 19,552 of my archive and is probably the reason i couldn't run chess without getting a memory error i don't want to know how much this is going to take up

It appears to be less than 500 KB on-calc, but I don't know if it's the complete game.

I completely forgot about this project, if I ever revisit it I would rewrite everything because I wrote it as a fledgling C developer. At the time I did do the math out and it could theoretically be stored in roughly two appvars worth of space (64kb each iirc? It's been a while) if I compressed the sprites and reused some assets a bit more wisely as some sprites are the same but with a different color palette. The biggest storage hogs of Undertale are the music and the sprites, one of those can be entirely omitted and the graphics are only large because they weren't optimized for storage. And to mention a previous reply, the effects would most likely be replaced with toned down variants. I have a Photoshop Flowey test program I made ages ago rattling around on a USB somewhere, I made it towards the last time I worked on the project, and it was ridiculously difficult to get the animations to look like Undertale and run at full speed. As of right now I'm working on other things but I keep all my projects up on Github because I sometimes like working on them. If I get a burst of motivation sometime I might make a new version, but as for now most of my projects I've posted on here are done.