Thanks a lot for the feedback, I'm glad you liked the grappling mechanics! The game will be surely polished a lot more in future updates, and we plan on fixing all the things you listed, and more! :D
As for the checkpoints not working, did you click on "Retry?" or "Reset Level"? Because if you did I don't blame you, many got confused and the menu will be reworked to be more intuitive (many, including my friends who playtested, said it looks like a title).
As for the sound effects, a theme and new reworked sound effects will be added in a future update! (we did the sounds last second, other than the death, rope, wind and walk sound effect, it's all me doing noises with my mouth and edited in audacity haha)
Stay tuned! ;D