Answer: Space Invaders

Although quite simplistic by modern standards, Space Invaders broke a whole lot of ground back in 1978. It was the first game that features enemies that fired back at the player, the first game where players were given multiple lives, and the first game to feature a continuous background soundtrack. While all those are notable and certainly influenced future games, the real innovation that kept players coming back was the high score board.

Space Invaders was the first video game to record high scores between plays and allow players to immortalize themselves by signing their high scores. As such it gave players a reason to return to the game, check the scoreboards, and attempt to reclaim (or further cement) their status as a high scorer. Persistent high scores coupled with a leader board proved to be enormously popular and the practice has persisted over time both in the arcade and with home video games.