A curious non-arcade adaptation from Sega's earliest days as a home video game manufacturer, Sub Scan allows players to guide a warship along the top of the screen, patrolling the ocean for enemy subs below. A radarscope at the bottom of the screen gives a small bit of advance warning of approaching waves of enemy subs. The player must use careful timing to launch depth charges to take out the subs, which travel in columns of four. If too many subs survive long enough to disappear off the radarscope, the game is over. Occasionally a bonus sub will appear, and the longer it's allowed to linger on the screen, the more points will be received for sinking it. Any bonus subs that escape unharmed don't count toward the total points required to end the game. Sub Scan isn't an especially fast-moving game, and sometimes it isn't especially exciting either. Graphically, the game is sub par when compared to games being released around the same time for the Atari VCS by Activision and Imagic.