History of Nintendo
In 1972, the first commercially available video game console, the Magnavox Odyssey, had a light gun accessory, the Shooting Gallery. This was the first involvement of Nintendo in video games. According to Martin Picard in the "International Journal of Computer Game Research": "in 1971, Nintendo had -- even before the marketing of the first home console in the United States -- an alliance with the American pioneer Magnavox to develop and produce optoelectronic guns for the Odyssey (released in 1972), since it was similar to what Nintendo was able to offer in the Japanese toy market in 1970s".
Space Invaders
As one of the earliest shooting games, "Space Invaders" set precedents and helped pave the way for future titles and for the shooting genre. "Space Invaders" popularized a more interactive style of gameplay with the enemies responding to the player controlled cannon's movement, and was the first video game to popularize the concept of achieving a high score, being the first to save the player's score. While earlier shooting games allowed the player to shoot at targets, "Space Invaders" was the first in which targets could fire back at the player. It was also the first game where players were given multiple lives, had to repel hordes of enemies, could take cover from enemy fire, and use destructible barriers, in addition to being the first game to use a continuous background soundtrack, with four simple diatonic descending bass notes repeating in a loop, which was dynamic and changed pace during stages, like a heartbeat sound that increases pace as enemies approached.