This is very nice. My only gripe is about chasing the flags for coins during the battle - or, rather, if I win the battle too fast, I miss on the extra loot. :p Otherwise it had a perfect gameplay loop to hook me in, I just had to play it through in one go.
Very neat. Using the UP key for both jumping and water direction was a bit problematic, though! I accidentally jumped into the fire a few times because of that. But a nice jam game nonetheless!