The story length of Super Dragon Ball Heroes World Mission varies depending on how quickly you progress and explore all the content. But generally, it can offer several hours of gameplay and story.
Gula was a character in Dragon Ball Super. He was Flisa's older brother and had higher strength and potential than Flisa. Gula appeared in the movie version and Dragon Ball Hero, and showed his powerful combat ability. His form was more advanced than Flisa's, and he had even forced the Super Saiyan into a desperate situation. Gula's strength and potential were obviously higher than Fliesa's, but he disdained to compete with Fliesa for the throne, so he did not become the emperor of the universe. Although Gula appeared in the movie version, his strength and character status made him included in the official history of Dragon Ball. All in all, Gula was a powerful character with potential, and he had a complicated relationship with Flisa.
One idea could be Goku exploring the full extent of Ultra Instinct in a new tournament. He could face opponents from different universes who have developed unique abilities to counter Ultra Instinct. This would lead to intense battles and Goku having to dig deeper into his power.
A fanfiction could explore Gohan's Ultra Instinct in a training scenario. He could be training with Piccolo or Vegeta, and they are both amazed and a bit envious of his ability. Gohan then uses his Ultra Instinct to help them understand new ways of fighting and power - up techniques. This would strengthen their bonds as comrades and also make them more formidable as a team in future battles.
According to my current knowledge, there is no official sequels or extras for the God and God of the Dragon Ball. Although some people claimed to have seen a work similar to the sequels, the officials did not give any relevant information or confirmation. If you want to know more about the Dragon Ball God and God, it is recommended to read related novels or comics, or consult the author or bookstore.
One idea could be Gohan struggling to control the new power of the Super Saiyan God. He might accidentally cause some destruction while training and then have to deal with the guilt and the fear of his power getting out of control.
Beerus. As the God of Destruction, Beerus has incredible power. A story could be written where Beerus decides to test Goku's Ultra Instinct to its limits. Beerus' unpredictable nature and vast power would make him a formidable adversary for Goku.