Maze 999

Players must grab their weapons and descend into several labyrinthine floors, full of monsters and hazards, in this 2D FPS. Each level has a mix of baddies and collectibles, plus damaging tiles and/or conveyor belts to complicate movement. You start on a safe floor with other NPCs roaming around; later stages delve into horror, cyberpunk, and fleshy aesthetics. Maze 999 uses the developer's own raycasting engine, rendering the world a la Wolfenstein 3D.