Pretty good game! Filled in your Google Docs form with a lot of feedback, but summarized: Love the gameplay, theme and music, don't like the sluggish feel the game has to it.
Oh, btw, an option to show the full map so far would be nice!
Two additional bugs. Sometimes when shooting an enemy with multiple bullets the game speed / framerate drops dramatically, until that enemy (or another enemy) is killed and disappears. The second bug is that I had the 'leatherstep' upgrade and the +3 Movement speed indicator remained stuck on the screen.
Bug also reported in the Doc, but whenever an enemy gets stuck in the wall, especially when it's on an island, you sometimes cannot kill it anymore, as the bullets hit the wall before reaching the enemy. This really sucks, because you can't progress anymore and have to reset the game. Sorry to say these kinda bugs greatly decrease the joy of playing (and finishing) your game :-(