I have just played it and have a few thoughts.
First impression: the graphical style is just awesome :). Chromatic aberration works really well here. It reminds me of Far Cry 3: Blood Dragon.
After playing a few levels: I like the way you teach the player new mechanics. It feels really natural. It gave me this satisfaction of learning something new, this "a-ha" moment :). All of this with only slight amounts of text :D. Also the way you kill the "wave" enemies feels great. Almost like slicing a fruit in Fruit Ninja :D
Almost at the end of the demo: Further levels bring a little bit of frustration. I had to restart them a few times before I got the hang of it. But when I finally finished them I felt REALLY good :D. I think it's because this game is all about player's skill level (kind of like in Dark Souls). I really like the fact that the succes or failure depends only on me and not some statistics / fancy weapons etc.
Now there are a few negative things I would like to point out.
The biggest thing I didn't like was the fact that the rope shortens itself on it's own. It was often frustrating and hard to accurately predict (at least in the beginning). I would prefer to be in full control of shortening the rope (by holding the "W" key for instance). Maybe even extending the rope by holding a key isn't a bad idea... :). Anyway I wonder was it a conscious decision to make the rope shorten itself?
There were a few moments where I have just finished an encouner with enemies (a batch) and I was really low on health. Obviously the next encounter ended in me dying almost instantly from one shot. Did you think about adding a way to regenerate health (either by itself, by picking a "health pack" or after killing an enemy)?
In the "Variance" level there were not enough points to hook your line. It made it unreasonably hard to juggle around enemies. Other levels didn't have this kind of spike in difficulty.
Also the giant in the final level suddenly changes direction of movement. It looks like he is teleporting. This makes the fight harder then it's supposed to be. It would be good to add an animation that would smoothly transition from moving to the right to moving to the left.
In summary this game feels really good to play and it looks quite well :) Keep up the good work :D. Oh and sorry for my "not perfect" English. It's my second language and I'm still learning :D.