Just an FYI, if you want credits on a game, try pushing the coin eject buttons. The last time I was at The Arcade, I saw a sign on the Simpsons that said to push the eject buttons for credits. This meant I could add my own credits to TRON and Gauntlet and others without asking the staff. The staff should have mentioned this "feature" when I paid as I had not seen or heard of using coin eject buttons like this.
Enjoy.