The exploding of the blocks is very satisfying, but the gameplay seems to end with just shooting all the blocks. I would have liked to see some kind of hazard (e.g. enemies shooting things at you while you search), or puzzle (i.e. limited arrows, and hints as to where the heart might be).
Also, the controls were a bit awkward with the mouse and the arrow keys. Using WASD with the mouse would have been more natural (at least for a right-handed person?).