N-Sub

N-Sub is a fixed shooter arcade game that was released by Sega, in 1980; it runs upon their Vic Dual hardware, and appears to be based on Data East's Tomahawk 777 (which was released earlier in the year). The player must use an eight-way joystick to direct that eponymous "N-Sub" around the waters at the bottom of the screen, with two buttons to make it fire torpedoes vertically and horizontally - and it can fire out three torpedoes in succession, if you hold down either button. The enemy fleet (which is always comprised of twelve ships) will attack the N-Sub by firing missiles, depth bombs and their own torpedoes at it; a round will end, after the attack by all twelve enemy ships (and the loop attack by the enemy destroyers) is over, and you will receive the 500-point bonus if you had killed all twelve enemy ships and all the enemy destroyers. The N-Sub will also receive an extra life, once you have reached the high score - and given that it does not have a preset high score (like many later Sega games do), you will receive it immediately if you are the first player of the day. All you have to do is kill an enemy.