It was fun for a few minutes, and the light mechanics attracting enemies has a lot of potential, but you become undetectable after a handful of muzzle flash upgrades, and the moths just hover in place as you mow them down.
Maybe give them some patrolling AI so the player is never truly safe.
Or perhaps make the player just as blind as the moths. Make moths harder to spot in the darkness without your muzzle flash. An element of stealth would make them far more dangerous.