Befitting of its name, this game is very frustrating and difficult, albeit very fun.
The movement is extremely fluid and responsive, the game is a lot of fun and it never feels like a level is impossible, which makes you want to try until you win. With that said, I have only finished the tutorial and started the countdown of the first level.
If you would like to make other games like this one, or simply extend this one, I believe that they should be made easier. When I try to balance a game's difficulty, I try to think of how many times I expect the player to "mess up" versus the amount of times that I allow them to "mess up". In this game, you have only one chance, making it very trial-and-error. An easy way to balance this out is simply by giving the player tools to "mess up" and be unharmed, such as HP points. However, if you'd like to keep the 1HP trait, I sugges that you give players the means to "scout ahead" (for example, move the camera slightly) and make enemies attack less often.
This was a very nice experience, and I hope I revisit it some time soon to complete something that is not the tutorial.