Your space ship is wihtin a nuclear reactor. At the center is the core whose walls are deadly for you if you touch them. Over time, the core starts to melt down and in the process starts to expand which leaves you less space to navigate. You share the precious space in the reactor with some particles which are not only attracted to your ship but will also try to bump you into the deadly walls of the core. You in turn try to do the same to them. In order to prevent the core to melt down the player has to bump all the particles into the deadly walls of the core. If the core has already expanded due to meltdown the player can try to bump the particles into two sets of four rods in order to reverse the process of melting down. After eliminating one set of rods the core will shrink back to its original size. To make matters easier the player can utilize decoys which will attract the particles. In doing so the player can maneuver the particles in an advantageous position for bumping them into the deadly core wall or into the rods.