Brainstorm is similar to Go-Moku in that it consists of players taking turns placing pieces on the playing field and attempting to get a certain number of their symbol in a row. Unlike Go-Moku, the goal is to get as many strings of three as possible, rather than to be the first to get a string.
Game play begins with the players deciding which of them will play X and which will play O. Then the fifteen X/O dice are rolled, and whichever player's symbol came up more goes first. Players alternate placing the dice with their symbols until either time runs out or there are no more dice left. This does mean that one player may get more turns than the other. This confers a substantial advantage to the first player, which the rules suggest can be balanced out by playing multiple games.
The final layout is scored, generally by counting the number of sets of three for each player, though the board also contains special double- and triple-score squares as well as some squares preprinted with X or O.
The player with the highest score wins.