I enjoyed the lore setup to the game. I also enjoyed the gruesome killing. Felt very satisfying to blast some enemies into pieces. A lot of stuff definitely felt like cool demo tech as well. There is definitely a lot to do in this game.
I thought a lot of mechanics were cool with some caveats. I liked the jetpack boost mechanic but sometimes it is pretty hard to use without 100% focusing on platforming. I feel like a little more forgiving platforming would allow you to do some fun fighting in the air with the jetpack (which was fun to use near the ground). The gun has a pretty small effective range, which I think also somewhat detracts from the experience and some of the cool combat you could pair with the jetpack.
While I liked a lot of the cool shader effects, I feel like they were just demo tech and not necessarily cohesive or contributing to the environment (which is fine, I assume one of your jam objectives was just to push tech). The level design was kind of wonky as well with some being linear and others having completely uncertain goals.
A lot of that I see you've addressed already as being a scope issue.
I enjoyed my time in it, congrats on the release.