Hi shadree. Glad you've enjoyed the game!
The "hidden" checkpoint was a last minute idea. I was gonna stick to the visual checkpoints only, but after watching some play testing with my kids, I realized there were some "advantages" in certain points of the game, and loosing was the easiest way to avoid playing through certain difficult parts, like caves you enter to flip a switch and then exit. I'll consider showing them instead of keeping them hidden.
About the level select, I struggle with myself NOT to put that, even when common sense told me to do it. I was eager to release the game after several months of working, so I stick to the autosave/load system originally implemented. After reading your comment, I think I'll revamp the Load Game system into the Select Level system, and maybe put a "Reset progress" button somewhere.
Thank you so much for playing and for your feedback!