Gorgeous graphics. Excellent level of juice and polish. Whoever did the voice lines for the boss character — that was really well done. I thought this game excelled in so many areas, control, movement, everything I pointed out in my opening line, but I thought the level design could use some tinkering.
I fought the first few enemies, but after that, I realized it was easiest to just evade and keep moving right. There was never a reason to stop and fight. Enemies didn't grant me any pickups or bonuses, and the checkpoints instantly refilled my health (I think that's smart for a jam entry so people can get further into the game), but after the first few encounters I just booked it to the boss fight. It sort of screwed me in that I had to kill like 8 bats in addition to fight the boss, but it seemed like the optimal choice.
The boss fight itself was great. The attack patterns and variation in attacks were well thought out and implemented except for two areas. I think the dropping boulders attack (gorgeous visual when he went into the background on that!) didn't leave enough telegraph time for proper reactions. And the pacing seemed a little off. There were only short windows when I was able to attack. The rest of the time I was just evading and waiting for my opening. There's nothing necessarily wrong with that. I think it would have worked great if the boss took more damage each time, but after a few rounds of evade and wait I was ready to take him out.
Overall, a condensed and fun adventure and a super impressive solo dev effort. Great work.