Thank you for the review.
The whole purpose of this demo is to get user data that will help us improve the game. The checkpoint system that you mentioned is under consideration and we wanted to implement it only if the game gets too hard for the players. Also for the tutorial buttons, you will have to pause the game and view controls for now. This will be fixed when the game comes out.
I really like your last point. I saw your video and somehow I guess you missed the last level (level 6 in the adventure section). Its a puzzle. I'm sure it will be an "aha" moment once you solve it.
These levels are challenging but there will be intermediary short levels between these long levels in the full game.
Thanks for the review! it means a lot to us and will help us further improve the levels.