I love this game's aesthetic! It's very concise, from art to music and sfx. Even the tile-based movement and simplified UI contribute, which makes this game not only retro, but convincingly so. It really feels like a classic, retro console / arcade game. This is the first I've heard of Pico-8, but you definitely used it to create a strong and focused vision.
Gameplay wise, I found it a bit confusing to figure out what was going on. I couldn't figure out how to find ammo or water, or what the different objects were scattered about the map, so I died without much of a fight. The water meter also blended into the background, which made it a bit hard to see. However... that's probably all because I'm incompetent.
So that aside, it was fun flailing my way around haha.