Zenith is a side view horizontal-scrolling shooter where the screen scrolls constantly. You have been tasked to fly your fighter through tunnels underground belonging to a secret alien force looking for total domination. As you fly you must shoot or avoid various aliens crafts over eight levels as well avoid walls because if you are hit then you lose one of three lives. In each wave is a flashing craft and if shot destroys the whole wave. At the end of each level is a boss and this requires multiple shots to destroy before moving onto the next level. A joystick is used to control your craft.