"Wreck-It Ralph” is the giddiest cartoon comedy in years. The more you know about video game history, the more you’ll laugh.

This kiddie version of “Tron” is set in a video arcade where, once the last quarter has dropped into the last game and the arcade has closed for the night, the characters travel through their electrical cords and mingle in the surge-protected power strips that connect them. Characters are free to visit other games. Everyone goes to “Tapper’s” for a root beer, though the barkeep has no time to chat with patrons, as anyone who ever played that game might imagine.

Clyde, the orange ghost from Pac-Man, hosts a weekly group therapy session for video game villains. Most of the attendees, including Major Bison from “Street Fighter” and Doctor Robotnik from the Sonic the Hedgehog series, are OK with being bad. But a lummox named Wreck-It Ralph (voiced by John C. Reilly) is having a spiritual crisis.