Super cool! Once I realized deleting blocks gave you more blocks, it became a fun loop of both trying to place boxes in front, and delete them from behind while still trying to avoid enemies and pick up stuff. Really great idea!
Two small bits of feedback:
First I would have some kind of screen at the beginning with instructions, and have it say that deleting blocks gives them back.
And two, when upgrading, I thought that each upgrade costed as many coins as the number above it was. The upgrade screen could be a bit more clear.