Quintic Warrior

Quintic Warrior is a single-screen top-down shooter published by Quicksilva for the Commodore 64 in 1983. The player's craft moves in all directions around a Space Dome while rows of Zorinian Mutants advance slowly up the screen, and losing all three lives is not the only failure state: one mutant reaching the top of the screen ends the game outright. The dome's own defences have malfunctioned and fire on the player from three guns at the sides and bottom of the screen, but their lasers are lethal only at the point where all three beams intersect, and a Zed Rammer periodically descends one side firing across the playfield.