The first arcade games where mechanical arcade games, these games worked completely without electricity such as shooting galleries, ball-toss games.
Sega introduced an electro-mechanical game called Periscope in 1966, an submarine simulator with a light gun. This game was a massive succes. In the USA it was the first game that cost a quarter to play. And this price became a standard for many arcade games until the late 90's. Besides Sega there where more EM arcade game manufacturers like Midway and Taito.