Retro 4 is a simple shooter game. The player controls a circle that can move around the screen by using the WSAD keys. Clicking the left mouse button fires a bullet towards the mouse-controlled crosshair. The bullets are used to destroy colorful rectangles that float through the screen towards the circle. The bullets are drawn towards the rectangles, as if through force of gravity. By clicking the right mouse button, the circle releases a large amount of bullets in all directions. If a rectangle runs into the circle, it's game over.