I remember distinctly - Pong!
I used to be 'encouraged' to do gymnastics one evening per week at the local Police Citizens Youth Club when I was in primary school - ie. before '78. I really disliked gymnastics, so part of the bribe to go was that I'd be allowed to play a single game of Pong after class. As soon as the class finished I'd race out to the machine when my father came to pick me up; it was definitely the highlight of the night - or even the week!
Next was Space Invaders, then Galaxian. After that it's a blur...
EDIT: Actually, Pong was the first arcade video game I ever played. I recall playing a completely mechanical car racing game, with the road on either a rotating drum, or a loop of material. The car was like a matchbox car on a stick, that was controlled directly with a steering wheel to move left/right. I can't recall how the game registered 'crashes' or whether there were any obstacles at all; maybe you had to simple stay on the road? The game was at one of the local shopping centres, and I was quite young, so this was probably early-mid 70's.
The shopping centre was completely demolished many, many years ago, replaced by a much more modern shopping centre topped by residential towers. I now have an office just up the road from there, and on the odd occasion I pop down at lunchtime, I'm reminded of that game.