It really is surprising that he developed such a complex (in a good way) system during the limited time of this jam!
The union of 2D and 3D was done in a very clever way, perhaps the best application I've seen for this genre.
The only bug I noticed during my gameplay was the popin of certain 3D objects, but I think that could be a limitation of the engine.
The buttons chosen for action/options/etc didn't seem the best either, but it's an easy detail to resolve.