Blockade is an arcade maze game developed and published by Gremlin in october 1976. Using four directional buttons, each player moves their character around leaving a solid line behind them, turning at 90 degree angles. To win, a player must last longer than the opponent before hitting something, with the first person to hit something losing. The game ends after one player gains six wins. Source: Wikipedia, "Blockade (video game)," available under the CC-BY-SA License.