Can i use my own project as a base? I'll remove any art assets and such, but can i keep my class structures and other such code which would speed up the dev process (implementation of top-down movement, custom flag system, etc), as long as it's not things such as gameplay design and content?

As long as you’re not making any game content beforehand, it’s allowed.

Alright, thanks. I guess i'm attending my first game jam then lol