Perhaps the most addictive puzzle game ever made. Part puzzle game and part action game and three modes of game play with over 90 levels, will keep you clicking. A never ending quest to reach Critical Mass, and reduce the Atoms to Dust. The concept behind Critical Mass centers on the real life phenomenon called critical mass, where if enough of a radioactive substance explodes it sets off a chain reaction of explosions.In all three game play modes you have the ability to rearrange a set of atoms in an attempt to group them with like atoms. When you have a group of these together(2 or more in Time Trial and Puzzle, but 3 or more in Progressive Mode) you can explode them. If there are enough of them you will achieve critical mass and all the atoms will explode. There are two ways to move atoms: 1) Left mouse button click, hold down, and nudge the direction you want to move it. 2) Left mouse click an atom, then left click on an adjoining atom The move will hold if there is a matching atom to either moving atom in their new location. If there is not a match on any of the four adjoining atoms, the atoms moved will return to their original location. You cannot select to move an ion cloud, but you can move them selecting an adjoining atom and swapping their locations.de.