Nice creepy vibes in this one. I do think that there could be some extra audio added when getting close to a monster, but I like the oddness of the mechanics and you explained them very well without slowing the player down.
I couldn't kill the first monster in the 3rd level because the gun wouldn't load the gunpowder at all, but I liked how the mosnter actually requires some skill rather than just blindly shooting it.
Something else that could be improved (which there might be in later levels) is a sense of urgency to reload & shoot while moving. The first couple of levels was just move, stop, shoot, move, collect ammo, stop, shoot, and you could stop for as long as you wanted with no risks.
I'm not sure where the reference for "skull island" came from, and it's not explained why you lost your arm, but I'm guessing you made another game in this universe that this is a sequel to? If so, cool tie-in but as a first time player it is a little jarring (why are we on the island? if we survived the island in the first game, why are we back? why are we only going out in a boat with one arm at night rather than daytime where it's probably safer? what's the story behind the monsters?)
But good job in setting a creepy mood :D