The Dragon Ball Heroes "game" as shown in the manga and opening trailers actually exists in one of the twelve universes and Supreme Kai of Time is behind its creation.Chronoa knew that there would be a need to handle twists in time that weren't obvious enough to catch the Time Patrol's radar. She also knew that one of the twelve universes had a prosperous Earth akin to ours that heard of the adventures of the Seventh universe's heroes. So she planted a "card game" into said Earth which would link the consciousness of its "players" into the scenario complete with a powerful avatar based off one of the warrior races according to their personality, theoretically allowing them to enter and help without putting themselves in danger as they can pull out back into their own world when they're beaten. The plan was to keep this project a secret, but with the escalation of the war between the Time Patrol and the demomic Time Breakers, she eventually told Xeno!Trunks about it, leading to him working with the kids (specifically Beat and Note) as allies of the Time Patrol.
WMG / Dragon Ball Heroes