Submarine Girl

You control a small submarine, piloted by the girl from the title, moving it through narrow underwater tunnels. Your main goal is to travel from left to right, shooting the various sea creatures that swim into your path. You use the arrow keys to navigate, which requires careful maneuvering to avoid collisions with the walls and enemies. The spacebar fires your weapon, and you often need to hold down the fire button to clear a path. The game moves at a steady pace, but the tunnels can get tight, making some sections surprisingly tricky. It feels like a focused, slightly claustrophobic dash through a hostile aquarium.