Ah, that explains the slime situation. I thought it was a fixed amount of time, so I just held a button and waited, before finally getting frustrated and spamming the keys :D
I guess that, since you have so many mechanics in your game, you should probably explain them in game as they get introduced. It also took me a while to figure out that the spikes also affect the rope, while all other stuff is only concerned with the hook. Its a fine mechanic that way, but it's not intuitive at first and probably requires some further explanation. Or you could visualize it by visually snapping the rope when the player hits a spike, but that's a lot of extra work of course. I know you explain everything in the description of your game, but I think that 99% of people (including me) are to lazy to read the wall of text and just want to go straight into the game.
TLDR, include a tutorial/explanation within your game. (As I also found out with my own game)