Took me a moment to get the hang of swapping between the screens, but I quickly got into a flow state once I did. Great gameplay loop that I think has a lot of potential beyond just a jam game, which I think says everything.
I had a little difficulty making out the bullets and enemies. Perhaps they could have been larger on screen, or make to stand out from the background more, like with a border. And I'd have loved some juice for killing the enemies, such as a sound effect so I'd know I hit the enemy even if I went off that scene view (though the map was awesome for that!)
A very solid entry (and looking at the comments, making this in your own engine is crazy impressive, sheesh)!