I love the idea and theming for this game, especially the boss battle. A trench coat full of rats is a great creepy boss idea, and the animation was great too. The blinking red eyes in the darkness was a nice touch.
I liked that there was optional backtracking to get powerups. However, the overall experience was very linear, it didn't feel like an interconnected world. I think if there were more "loops" in the navigation, where you could end up somewhere you had been before but with more abilities this time, it would be more interesting to explore.
I found that I didn't use the knife hardly at all, except for the boss battle. It was very hard to tell when I was close enough to hit something, and the range was so small I was very likely to bump into the thing I was trying to hit, so it was always easier to just avoid the enemies altogether. I think if the range was larger or more clearly indicated, it would have been more interesting to use.
I enjoyed all the movement upgrades, jumping and gliding was very satisfying. I wished there was some indication of how many wall jumps I had left, or even simply no limit. I thought it was just glitching out and not working sometimes, until I got the first powerup that said it increased my wall jump capacity and realized what was happening. Overall though, a great set of mechanics. I especially liked the section where you floated through the room of steam pipes, riding the warm air and dodging the projectiles.
Thank you for sharing this game, I enjoyed it.