Pretty cool! I didn't realize you could basically fly via double jumping at first so it took a while to find all the keys until I tried double jumping for the first time. I also found it confusing that all the keys didn't seem to match the flag colors even though the first key I picked up was blue. But overall I had a good time, great work!

Loved this one 

There is however a glitch in the last boss where if you go behind and run toward the NPC,you can just keep hitting them without them moving or turning around

just thought I point that out 

overall good game