This is super well polished. I am especially a fan of the pixel art style you went with. Everything fits in a cohesive theme and really makes the simplistic world design come together. My only real gripes with the game involve the relatively slow movement speed of the player. Because of how slow the player moves it makes combat tedious and unnecessarily challenging at times due to how close you need to be to attack in conjunction with the speed of the projectiles shot by slugs. This could be easily tweaked, and as such I do not think it harms the package as a whole. Overall you have showcased a strong understanding of cohesive game design and polish. Great work!