The jetpack feels really nice to use. It has weight to it and I almost think a whole game around such a jetpack might be a lot of fun. I only got as far as to Level 3 but I like the aesthetic of a bunch of rooftops and you have to explore to find the way through.
There's a lot of problems with the game design though. For starters there's no way to recover health and I find that irritating. There's no reason to fight the small enemies too other than to get ammo but u can also save ammo by not fighting them. I think there should be some kind of indicator of which weapon you're holding at one time. There should be options for mouse sensitivity and turning off/on music (although granted I didn't do that too in my game). I do like the way the text pops up and faces you when you're near a weapon, I thought that was kind of cool.
The game's concept of just shooting enemies and dodging their projectiles while u have a jetpack is fun but the execution could be better. Aiming feels really stiff prob due to no sensitivity options. The way projectiles move physics wise is interesting especially as it allows me to try and dodge enemies. The music is kind of repetitive but also not too annoying. I do wish there was a way to turn it off.
I noticed some technical problems when on the third level. I think the person who coded projectile physics and collision and projectile spawning could have done more to optimise the code (Projectile Pooling, don't use too many GetComponent calls during Update()) but without seeing the code I won't be sure what was causing the problems. The game shouldn't have lag spikes for a game like this on my computer which is capable of running way more graphic intensive games at full settings.
I won't mind a game centred around exploring a city skyline with a jetpack and a gun (maybe even a sniper) that level 3 suggests. It's a fun idea.