Blockade

Blockade is a monochrome arcade maze game developed by Gremlin and released 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.
Blockade is the first of what would become known as snake games.