I used to go to a local Pizza Hut that had a Ms. PacMan/Galaga arcade cabinet up front. During the pre-scripted onscreen demo for Galaga, after one of the ships is captured and shot free, you can move the joystick left or right to gain control of the ship and start playing without paying anything. Eventually, the cabinet either crashes or the demo timer runs out in the background, and you lose control, but it was always fun to play for a few seconds as a kid while the "insert coin(s)" prompt was showing. I found another Ms. PacMan/Galaga cabinet recently that I could still use this trick on, meaning that this glitch is likely present in all of them.
I used to go to a local Pizza Hut that had a Ms. PacMan/Galaga arcade cabinet up front. During the pre-scripted onscreen demo for Galaga, after one of the ships is captured and shot free, you can move the joystick left or right to gain control of the ship and start playing without paying anything. Eventually, the cabinet either crashes or the demo timer runs out in the background, and you lose control, but it was always fun to play for a few seconds as a kid while the "insert coin(s)" prompt was showing. I found another Ms. PacMan/Galaga cabinet recently that I could still use this trick on, meaning that this glitch is likely present in all of them.