Speaking of the earliest hits in arcade games, 'Pong' is known. Nolan Bushnell, who worked on 'Pon', actually released a work called 'Computer Space', the world's first arcade game. As for why ...

I remember seeing and playing a Pong game in a San Francisco arcade. AKA 'Brickout', it was bery simple. About as simple as you could get, and the downtime 'auto-promo' told you everyhing you needed ...