I had really much fun playing your game! You managed to create loads of content in your game in such a short time. Nice variety in powerups, I of course went for a full dmg build, and it was super fun! For me, the confined mechanic was really nice, it was cool to see the mayhem unleash when the effect wore off. I also liked that you added some bullet spread to the weapon. The weapon reminded me of the cooperative character's starter weapon in Enter the Gungeon. Some things that could improve the game:
- clear information about taking dmg, I died because I didn't realise that I had taken dmg, I even had loads of hearts lying around waiting for pickup (the fact that hearts stay in the ground is a nice thing, though)
- the controls felt a bit slippery, I think super precise movement would work better in a game like this
- some optimization would be in place, since my computer had quite a hard time in the later levels using confined mechanic, as there was zillions of bullets on the screen at the same time
- adding some juice to it! Like screen shake, particle effects etc
- adding more melee specific enemies (the melee weapon upgrade felt a little bit niche)
- the music of the level felt a bit off considering other aspects of the game (that's of course personal opinion, everyone enjoys music in different ways)
For a game made in 10 days, this was superb! I definitely would love to try out updated versions if you decide to continue developing your game :)