Time Machine from Data East, at Grand Slam Batting Cages in Monrovia CA.
I had played pinball before at a great place in Pasadena called Pak-Mann Arcade, in the late 90s. They had a good selection of the WMS games (plus the inescapable South Park), and I remember them getting Revenge from Mars and Episode 1 when they came out, which at the time I was too young to understand the significance of. I loved playing pinball then just for the kinetic action of the ball, and had no play strategy other then keeping the ball away from the drain. Getting the ball onto a ramp at all was the coolest thing ever and enough to constitute a good game for me.
Later on in middle school, I was looking for any place to play arcade games near me, and found Grand Slam, where Time Machine was the only pinball they had. It was the first non-DMD game I ever saw and the presentation of it was captivating. The great music and sound (especially that incredibly cool "singing" vocoder robot voice) drew me in, and the simple rules started turning gears in my head and got me to think about how to start and complete different scoring features. I remember looking up the different flipper techniques for the first time one day before walking over to Grand Slam to play, and I tried nudging for the first time shortly after. Time Machine is the game that elevated pinball from something I liked to play now and then into my favorite game of all (pardon the pun) time.