Good job trying to make a tower defense for the jam that is hard. I am curious to know how you did the navigation. I like the 3d assets it's a pretty game. Jumping between the two planes wasn't very fun, though and is just hard to keep track of. I also don't think you followed the Combine theme.
I’m using https://github.com/vleue/polyanya , my implementation of https://www.ijcai.org/proceedings/2017/0070.pdf in Rust. I had a lot of issues building the dynamic navmesh, it took me way too long and I had to cut short a lot of ideas due to that…
The “combine” part is that you have to combine your defenses on the two different planes.