The series has become extremely popular in recent years due to its sharp humor and satirizing elements, such as its protagonist being constantly bored due to his ability to defeat any opponent with one punch. Season one revolved around Saitama, a bald-headed man who sought adventure and good fights, but was insanely bored due to his power, which allowed him to win those fights instantly. It was a gimmick which worked well due to the fluidity of the animation studio and the running gag.
Season 2 lost that fluid animation due to a shift in studio, but also focuses on other characters, as watching Saitama win without effort had run its course.
The fighting game will be a 3v3 fighter, taking characters from across the series, even Mumen Rider, a C-Class hero with a bike who's more of an everyman and can barely fight. Other characters included in the trailer are Saitama, the cyborg Genos, Fubuki, and Speed o’ Sound Sonic. Some characters from the trailer were only introduced in Season 2.
The backlash for the change in animation between season 1 and 2, due to season 1's fluidity and ease of movement has been felt strongly by fans in the community, meaning that season 2 is held up by storytelling alone. The question now is, what will transfer over to the game? Will it be a story-rich experience amid the fighting?
More than likely, Saitama will get a downgrade, as he's been shown to be invincible in the series, taking punch after punch by a world-ending superboss and shrugging it off. Transferring that over to a fighting game, where characters are balanced, would be difficult, especially with Mumen Rider on the scene, who is famous for dealing absolutely no damage and yet being a swell guy you want to root for.
The game currently has no set release date, but look forward to the mobile game, One-Punch Man: Road to Hero coming out after the conclusion to the second season.