cool idea! although the Quetzalcoatl is pretty hard (I got it to 5 hp, but then died) I like how you implemented the health system - it looks like a good way to stop players from speedrushing that enemy. Also the switch to the ground battle was fun. Maybe it would be fun to give the switches more meaning (instead of giving the player the choice, you would always descend after losing the sky battle and always ascent if you win on the ground?)