Wow, this is a good looking platformer. Not exactly sure the ties to the theme, but it feels solid. I found the rat king but couldn't defeat it. I think that's maybe more of a skill issue though. I need to git good :)
I think the game may benefit from having an explanation of the controls though. Something easy might be to have the controls on the cave walls at the start or maybe throughout the level. I kinda just resorted to pressing all the keys on my keyboard to see what does what. Having J to attack made no sense to me at all. I think at one point I accidentally found a heal mechanic. And now that I'm looking at the title again I think I might've found the "rewind" mechanic while stationary, so I don't think it was clear what had happened.
Also, I'm not sure if the tent was meant to do something. It kinda stood out from the background a bit so I thought I was supposed to enter it. I think that's when I tried pressing all the keys, but I couldn't figure it out.