Fun game, I get the disco theme, great design, just wished the colors were a bit more muted or less eye-straining so its easier to play longer. 

Really good game you made well done! The graphics are really effective, and the music fits well with the game. And I also like the fact you made a lot of enemies chasing me, which makes it look hard.  However, if I had to say something you need to improve, it would be the fact the gun and the hitbox. The gun comes out of nowhere makes it confusing. And I think you made the player hitbox way too small. Although the game is really fun with like the 100 enemy ai movement mechanics. 

Good luck :D

Interesting take on the bullet heaven genre. The music was cool and the screen effects were kinda fun. It's clear you were going for a chaotic atmosphere. Unfortunately, almost all of the tweaks to the formula made it worse for me. Here's how a typical run went:

• Map starts, there's a gun nearby. But don't pick it up! You'll waste limited ammo.
• Enemy spawns. Now it's safe to pick up the gun. 
• Fire at the giant red cube. (Gas pump?) 
• Bullet goes right through giant red cube without hitting it. Try to aim at its center of mass? the ground beneath its feet? The white dot you can't see half the time? Where's this thing's hitbox!?
• More giant red cubes start to spawn. Eventually, if the horde gets big enough, I'll start hitting some of them, I guess.
• Every few seconds, there's a lag spike. Not sure what's causing it. Maybe it has to load the gun model every time you get a new gun?
• Speaking of which, having to go and get a new gun every 5 seconds is annoying. Half the time, it spawns in the middle of the horde. I can't imagine a 2% chance of getting an SMG instead of a pistol is going to save this mechanic.
• My hands tense up every time I'm forced to go near the edge, every time I'm forced to jump, every time I realize my gun stopped working... pretty much any time anything that makes this game unique happens, my blood pressure goes up.
• Let's talk about jumping, by the way. My back is to the wall. There are enemies all around me. I have a double jump ability. I'm mashing the spacebar. Why my character not go up? That was rhetorical. You're using Unity, so the answer is probably you used a Rigidbody instead of a CharacterController.
• You really need to be more generous with the hitboxes, man. Each enemy should have a hitbox for world collisions that's the same size as the mesh, a seperate hitbox for player bullets that's a bit bigger, and a third hitbox for damaging the player that's a little smaller... oh, wait, you used Rigidbodies for everything, I forgot. Make the player bullet hitboxes bigger, then. No, wait, then they'd hit the world geometry when it doesn't look like they should. Okay, so give the player bullets a larger enemy-collider that fits like a shell around the world-collider. I'll take anything. This business of firing into a crowd and somehow missing half the shots is ridiculous.
• If the bullets moved faster, it would really make it a lot easier to hit what I'm aiming at. I believe Unity has a physics setting to brute-force solve the problem of projectiles "ghosting" through colliders, and if that's too computationally expensive to use, just use box colliders for the bullets, but stretch them along the bullet's trajectory so you're firing long rectangles that get longer the faster the bullet is. 
• (IMPORTANT: change the Box Collider numbers. Do NOT scale the bullet GameObjects! It'll break the physics collision process entirely if any physics objects are scaled to non-uniform proportions!)
• Actually, could ghosting explain why I'm missing all the time? I dunno. The bullets seem pretty slow. It doesn't look like they're moving fast enough for that to be an issue. Then again, at these frame rates, I suppose anything is possible.

I hope you improve the game. You've got a nice theme going. Now you just need to focus on the fundamentals. Your movement, jumping and bullet collision need to be, well, bulletproof. 

Good luck!