Hi there! Many thanks for checking out the demo and for the lengthy post with all that feedback, really appreciate it!
About the boss, I think the current level of challenge is fine. Don't forget that's the first boss of the game! If I make it harder, other players might get frustrated and quit right there.
Happy to read that you liked the secret hunting. I'm the kind of player that loves looking on every nook and cranny and being rewarded for doing so, so you can expect a lot of that in the final game. :)
Thanks again! And have a good one.