This has potential. It's got a good amount of mechanics, which all work better than I expected them to.
The grapple hook is pretty responsive and quite fun. Being able to shoot your gun straight down to gain a little extra height is excellent, and combined with the fact you only have a few bullets before needing to reload ensures its not an overpowered ability.
With a bit more development time, this could turn out pretty good, as you've got a good foundation to build from already.