As one of the earliest shooter games, it 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. It was also the first video game to popularize the concept of achieving a high score, being the first game to save the player's score. It was also the first game where players had to repel hordes of creatures, 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 chromatic descending bass notes repeating in a loop, though it was dynamic and changed pace during stages. It also moved the gaming industry away from "Pong"-inspired sports games grounded in real-world situations towards action games involving fantastical situations. "Space Invaders" set the template for the shoot 'em up genre, with its influence extending to most shooting games released to the present day, including first-person shooters such as "Wolfenstein", "Doom", "Halo" and "Call of Duty".