I liked this game - small, compact, with some replay value. I had some problems fighting the physics, the player balance is hard to do in this type of game (and for example THPS cheats in this a lot). I love the exploration aspect and the previous try ghosts.
The game could be focused more on exploration. Imagine giving player a random city (perhaps composed from pre-modelled blocks) with randomly placed stars. Imagine various environments, ground, underground, sky high…
But first, polish the physics itself. It is the only thing missing in the game jam perfection. (The rest was already said by Radek and Rudolf, and I have nothing more to add, as I have same opinions on your game.)