This is a neat idea. I had fun swinging on level 1 and skipping all the platforms. However on level 2 I was a little frustrated when going for the final platform. I had a hard time telling if my grapple was in range of the colored blocks. I started going for the fast platform and had difficulty landing on it because my zip would leave me floating and the platform would just fly away. Something that would hugely improve this is just adding a prominent shadow under the main character. That way you can tell where he is and when he's over something. Also having better indication of whether or not your grapple is actually in range.
One more small thing, when I died in slow motion, the animations took a long time to go through and I couldn't click the level restart button. Also some of the sounds are a bit jarring. Overall though this has a lot of potential. I'd love to see this get fine tuned and released. Can't have too many platformers.
Good job on this :)