I love this. It feels like an adorable love letter to Super Metroid; the broken lab containers, crawling spikey enemies, and you even nailed the isolated rainy atmosphere of the surface of zebes! My overlying problems with the game are with the controls. The high jump is a bit awkward to use, compared to the rest of your smooth movements. Needing momentum to move with the high jump properly makes platforming difficult and tedious. Also, you forgot about the select button! Using metroid two which was on the gameboy as an example, you could swap between missiles and your normal gun by pressing select. (On keyboards, select is usually mapped to the shift key). Being able to swap weapons like this would make gameplay even more crisp.