I'd love a 3d version of this
I think "3D" and "1-2 month project" are incompatible. 3D is a big mess to do anything, whereas it's easy to blit some sprites.
Yup. Collider/mesh math is where the really esoteric, fun-killing bugs start to be introduced. 3D is cool, but on another level (hehe, literally).
Just use spheres