This is your most polished looking game yet, Sam. The mechanic is pretty solid and works well, the art style really adds to it.
The cardinal direction of your aim does not match the isometric directions of the map, but that's really the only problem I have with it.
If you wanted to extend on this, you could throw your boombox in the direction your aiming for a bit of damage, and it means you have to fight your way through zombos to get it back, rather than backtracking ever so slightly to where you put it down.
All in all though, great work as always.