I like this concept and the improvements on the technical design would make this game much more enjoyable. 

The projectiles to avoid move slowly making it frustrating, and enemies that look like they should only take 1 hit can take 3 or 4. This makes the combat slow and more of a nuisance than an enjoyable element. 

Great job with the grapple hook though, more use of this in the game would have been cool. Using it as an elevator or to create monkey bars to get over obstacles would be awesome. Far too often in platformer games the player has to wait for a floating platform. This kind of thing would be a good way to improve upon that traditional mechanic.