Atom Smasher is a single screen shoot 'em up with multi directional movement that takes place in a nuclear reactor during a meltdown. In the middle of the screen are some neutrons and a single proton which one electron moves around. To delay the meltdown the player has to shoot the proton but avoid the electron since that will speed up the meltdown for a short time. For each proton that is shot, an extra electron is released. As the game goes on molten debris will start building up from the sides of the screen and if it reaches the nucleus the game ends. It is possible to destroy debris by firing at. In the Amstrad version it is also possible to ram through it. When colliding with an electron one life is lost.