This feels unpolished, but I can see this evolving into a really slick parkour game. I agree with the comment below about removing the player's gun - it's pretty much unnecessary because this game clearly wants to be about movement, not about shooting.
I'd focus on how to make moving feel really good. What kinds of sounds can you add to footsteps and jumps to make them feel real? How can you arrange the platforms in interesting ways so that players have to puzzle-solve on the fly like real parkour requires?
As for the things shooting at you, think about placing them in such a way that it encourages your player to do the thing you want them to do. If you want your player to avoid taking a certain path, put a gunman or two there to discourage them and push them in the correct direction!