This game has great concept however the implementation of certain features hold the game back. One of the simpliest fixes I think you guys can implement would be to swap the mouse buttons so that shoot is left click and grapple is right click. As many people are very accustomed to left click being the shoot button. Additionally, setting space to at least be ungrapple would make the game very understandable. If a jump was added after it would feel quite a bit nicer. I highly recommend seeking a better wall climbing mechanism as the current one is quite unstable and extremely hard to use.
In terms of other features I think the fog is really nice, there are some spots you can hide from the fog but it seems well balanced for the current difficulty of the game. However most of the difficulty comes from the wall jump being inconsistent and the keybindings being awkward. I would suggest increasing fog speed after fixing those up.
Health is an interesting concept in your game as some of the obstacles where you have health its a touch nice to be given that leeway, but in most cases you insta-die anyways.
I found the rapid shotgun quite entertaining to use. It may be cool to have portions of the map where you're given the shotgun for a brief instant to pass a section. I think enemies might be a distraction as the fog is the major concern enemies would probably be rapidly dodged rather than defeated.
The level design is very nice and I really like the uniqueness of the obstacles you guys have implemented.