I played around with your game. It’s pretty hard, but I get the feeling it’s a game where you need to grind a bit before you can feel powerful. I think the mechanic you are trying to produce is solid. Lemme share some of the immediate feedback I had.
Regarding Audio:
I’d suggest adding a dry ammo audio clip for when you need to reload else.
Also, some reload audio clip would be nice to let you know when you’re ready to fire again.
Regarding Power-ups:
Are there any other than buying new weapons? Maybe a heal?
Eek! I feel like i needed a lifeline or sorts.
Regarding the rooms:
They are okay but maybe create a couple variations.
Also, I noticed you cannot collect coins until the room is cleared, seemed a bit odd to me as I was near death and wanted to collect a couple more coins to put towards a new gun.
Regarding the enemies:
I felt they moved a bit too fast, maybe this was intentional; however I’d argue the player should feel a bit more in control. Maybe up the enemy count so the hits you take are buy obvious mistakes you made (bumping into a wall or not reloading in time) instead of constantly running away from the enemy and having to kill them quickly.
