Neat little game!
I think the game could use an obstacle of sorts, or, at least, a way to punish the player if they drop the cube/play badly. I feel like something simple like a time limit could already do the trick, but adding negative-score cubes could also help!
Still though, it is fun to mess around with for a bit, and I do very much appreciate that the platform moves at the same horizontal speed as the cube, even when moving up!