I restarted until I managed to beat the boss with some hps left as the game is cool so it was worth beating the fair way.
It was fun! The game looks good and music is great. It controls well and you made a pretty great implementation of the theme with a super cool overall staging, it was cool at the beginning being surprised that there was no command to shoot, then the scale when you shrink is great (the map was welcome) and the game ends with a satisfying boss fight with 3 cool bullet patterns and the appropriate life bar. The difficulty of the boss fight was perfect as is, although I'm not sure it exactly works as intended like mentioned below.
The only thing I missed was some sound effects on hits.
I guess the rooms other than the boss could propose more of a threat. Also there seems to be invincibility frames but in the same time not, I don't really understand how it works, the boss fight was all the more fun this way but I think there might be something to fix although the game would also probably then need another balance pass (like giving only half hps to the player)
Thanks for sharing!