Interesting idea. Our team was thinking about someing quite similar in our brain stroming session, so it's extra interesting to see the games of people who went with such a concept.
On my first try I came across a bug where I could just move the cube through all walls, but after reloading the game page everything worked as intended =)
The minimalist and clean presentation of the game works very well and the small accents such as the pulsating player cube and the audio make the game feel quite polished in this regard.
Gameplaywise I would have liked for the game to get progressively harder or have some other tangible goal, like a par value to go for.
The controls worked well and reaching the coin felt like a good amount of difficulty if it spawned on the other side of the map: not unfair, but challenging.
All in all a nice entry, cheers =)