A fun strategy game! (Though I don't think it's from Compute!, I can't find a reference to it).
Take turns placing a single bomb into any place on the board (you cannot place a bomb in a spot that contains another player's bomb). You can place up to four bombs of your own colour in each spot.
When the number of bombs in a spot equals the number of adjacent horizontal and vertical squares, the bombs explode and scatter to the adjacent horizontal and vertical squares, turning those squares to your colour and leaving the central square empty. If there are enough bombs in those adjacent squares to explode, then they explode as well, scattering around, and so on...hence a chain reaction.
Corner squares require only two bombs to explode, edge squares require three, other squares require four. Because it's easy to create an explosion in corner squares -- and explosions spread your colour around the board -- it's useful to have control of those squares.