Well done! Solid gameplay, sounds, and visuals. Nice music.
One big thing I'd note however is that (at least as far as I played), there's never a reason to just not hold on your flashlight all the time. As you can shoot independently of your flashlight being on or not, I just held it down all the time which was uncomfortable just causing additional tension and strain on my mouse hand (I do have mild carpal tunnel). It's unnecessary. It's a very common game design mistake; often seen with top-down 2D shooters like this, actually, where you have infinite ammo and infinitely spawning enemies, where it's better just to shoot all the time, but the game requires you to hold the button down or worse to repeatedly click to fire continuously. As this game has friendlies you don't want to shoot, you don't have that problem with the mouse, but I just held down the right mouse button in addition at all times (I like I see you doing in your gameplay GIFs) which begs the question why it's not just enabled by default.
You could do a lot with this: certain enemies/friendlies are sped up or slowed down by the light, maybe it kills some friendlies (or even enemies), the flashlight is on a resource meter that ticks down as it's used but refills when unused, etc.
You could also make nice changes that similarly give the player more interesting decisions. Maybe you slow down your movement while firing, but the player doesn't really have a reason to move right now... So maybe there could be a weapon degradation system, and you move around to pick up new weapons. I don't love how the game is an insta-kill right now, so there could be basic numeric health and health pickups around the field. Maybe some slimes are invisible in the overworld unless you shine the flashlight on them (or vice versa!) or get really close to them. There are lots of simple changes you can make to shake up the game design.
Nice work!