What I didn't like:
The gravity shifts are more annoying than anything. It killed me several times and I spent most of my time just waiting for gravity to flip again. I only realized there was a timer at the top of the screen after beating the game since it was cut off on the screen (Unity browser builds are notoriously glitchy). This is a situation where I think extra polish would help, e.g. a big ticking clock with a ticking sound effect, etc.
The boxes seemed kind of superfluous, but I know that's just how game jams go.
What I liked:
The music was impressive. The graphics are serviceable too, especially minding that it's not pixel art. Overall for a two-person game this is decently produced!
[Spoilers] I really liked that there were little secret paths and a shortcut in the level! Adds some extra layers to it. Having control over gravity as a post-game power is nice.