Reactoid gives you a top-down view of the reactor core, the heart of Professor Albert Arnstein's experimental and top-secret power station. Twenty-four energy posts are at the center, surrounded by twenty particle emission tubes, any one of which could emit the next energy particle. You generate kilowatts (your score) by deflecting the particle into a post as it passes one. There's only one chance to get it right; after the first bounce off the reflectoid, the particle will just pass through it on a second attempt. If seven of those particles find their way to another emission tube, whether by shooting across the core undeflected or by your inept deflection, meltdown is reached. On the other hand, if you deflect particles into all of the posts, lighting them, you survive the round and are rewarded with a fresh start and two particles shooting across the core at a time. For each round you survive, the particles on the screen and the kilowatt multiplier increase. Three meltdowns and you're done, unless you've picked up a spare reflectoid along the way.