What does a green game listing mean?

If a game listed is highlighted in a dark green, that game was recently added to that location. If it is highlighted in red, then that game is currently off the floor.

Best place to look at this? Galloping Ghost Arcade. They are constantly adding games there. Also, some locations have an extensive warehouse or storage facility of arcade games and they rotate their inventory often. This results in games taken off the floor highlighted in red.

If you're referring to the bright green dots to the right, mouse over them for more information. It refers to the condition of the game.