Solid entry, I was a bit confused at first because I didn't know about the infinite shot, so I lost a lot of time in the second level.
But once I figured it out it became really fun! Well done! (300.19s)
Thanks for the rating! Our game being described as solid is more than I could've hoped for xD. The shotgun overflow is supposed to be introduced in level 4 (although you can certainly still use it before then) so that if you replay the game you can find new clever tricks and shortcuts in the earlier levels. Ideally it would be communicated better, but we were on a time crunch ;P