Yeah this is actually amazing for a gamejam. Great use of colours to contrast the player, boss, and arena. Feels nice to control, boss looks awesome.
Always love when games have the way of health recovery be based around attacking your opponent, which is used very smartly here.
It was a very smart use of time to spend the jam working on a single boss fight, quality over quantity.
Great game.
Edit: Beat it on hard mode, extremely fun time.