For a compo entry, this game is amazingly well done. A lot of attention to many details here -- the pirate ghosts, the parrot animations, the BOSS FIGHT (in a Metroid-vania compo game WTF?), and the general game progression. A lot of good stuff here. AND you had a tutorial that guided players through various game input while you proceeded through the start of the game. Are you Compo Jesus or something? c___c
There were a few things that did nag at me and I did have trouble with, however -- the camera is definitively your enemy. I know that the theme was quite restrictive, in terms of the entire game on one screen, but I think the flippy-floppy trouble that I had originated simply from the level design, and having too many important things close to the edges of the screen instead of in the middle of the screen. The player controls were a little bit sticky in terms of jumping and shooting the cannon (my mouse would flip around sporadically at times, depending on the direction of the screen change), and there were a couple of jumps that were quite hard to achieve -- but it wasn't bad enough that I couldn't get through the game. The biggest obstacle I had a problem with was the spikes -- largely because they often were located in tight areas that were hampered by the camera, and if I hit the flat side of the spikes I died instantly.
I might also suggest a better way to identify where a key is .. either via particle effect or sound or both. This would have to be implemented very well to keep from being annoying, of course. :)
Also, I did not realize, at the one end of the screen, that I could jump over the barrier and into the water. Some indication, such as a dock, item, etc, that you can go in that direction/walk on the water would be stellar. :)
Overall, this is fantastic for a compo entry. REALLY good work!