Ohh man, i've just played your game, love it... Great job...
So, now, time for my wishes about your game..
1: i would like to see some sigils on buildings because of too much buildings..
2: actually game isn't too hard, but it feels like that until you get how to do it, so, you may award player with some little help windows about how to beat enemies easily(only for beginning levels + first boss) to keep player in the game.
3: you can change stage.quality to "LOW" at the beginning. That doesn't affect game quality in pixel based games but it has great positive effect on performance.