Very nice game with simple but great looking visual and sounds. I very like the usage of the"border" ingredient. There are just 2 problems I had with the game:
1) The close-range mushrooms could benefit from a better pathfinding. Right now, they often get stuck on an edge an obstacle and are unable to move on.
2) I see the benefit of being able to shoot in the opposite direction than you are moving in (using the IJKL keys), but this benefit this is kinda killed by the fact that the character stops to shoot. You could get rid of the IJKL keys altogether and just make the character shoot in the way it is facing. It would not make any change to the gameplay, and make the controls simpler.
Overall, a very nice little game with good coherent visual and audio fitting the jams theme nicely. I can totally imagine that playing this game on a "gameboy like" device would be a total blast!