oh man this was a lot of fun! i love this concept of losing interest, allows for players to explore the different types of weapons in your game, make it a lot more engaging! it also helps that the weapons do feel pretty different in terms of how they're used, so it adds to this feeling of coolness when you go running around shuffling weapons and firing at will (especially when you throw them away too)! the interest meter also encourages the player to act aggressively instead of defensively too, which is always a plus in my book! one thing though is that sometime im not sure how i was able to get health back, don't know if its when i pick up a rare gun or not.
the aesthetic looks really nice too! really love the pixel art, especially the gun sprites and materials! they all look differentiable and easy to identify from each other (the white outline helps out a lot in visibility)! i also like the player and the enemy sprites, though there were some situations where the enemies blended too much into the background i feel (especially in the cave). sfxs felt really chunky and powerful which gave a weight to each action that it corresponded to, which felt pretty nice!
this was a pretty fun game, this would be a cool game idea to expand! great work!