Williams Travel Time from 1973 had the duration of play controlled by a playfield clock with selected targets adding time. As a kid, I loved this feature of trying to beat the clock and the EM Williams machines from this era.
Travel Time was my first machine to own. had the SEGASA version and got it for free about 20 years ago. I eventually sold it and found selling the first game to own a liberating experience, although i must admit i do miss the machine and the Segasa version had better plastics and backglass... great knock about game, excellent example of 70's Williams keep the ball alive game