ZDoom

This TC looks promising but might I recommend philfering some extra assets from Claymates on the SNES?

Some of the stuff from Claymates might fit (Their art-styles are strikingly similar) and be useful in H.U.R.L. I can't help but to feel that Claymates music, sound effects and graphics would work nicely with your project

I'll look into it! Thanks for the recommendation, didn't even occur to me to check that game or similar ones on the snes.

Playing through the levels and they’re alright; they’re structured a bit better than the original game. And about enemy variants; maybe have the flies be their own distinct enemies instead of just frog projectiles. Maybe also an alternate version of the frog with a different projectile before you meet the variant with flies.