I had a lot of fun with the grappling mechanic, that is very well implemented. the wall climbing felt a little slow but was mostly fine. I got to the exit but couldn't go through it. Do I have to kill all enemies before exiting?
I suggest adding a way jump off a wall you are climbing. that will be nice to combine with the grapple swinging mechanic.
The art gives a nice retro vibe and the music fits the theme.