YMMV / One Punch Man: A Hero Nobody Knows

• Anti-Climax Boss: The Final Boss of story mode can be defeated with one regular attack. And for once, this is not justified by you playing as Saitama. Because those who're familiar with the source material are aware that Boros's Healing Factor is so strong that he was able to survive regular punches from Saitama there. (It was still a Curb-Stomp Battle, but Saitama had to put in more effort than usual.)
• Just Here for Godzilla: The reception for the game, from it's initial announcement through release was pretty lukewarm, but a number of people were interested on the sole basis on how a fighting game would try and balance around Saitama.
• So Okay, It's Average: The general consensus of the game - it's a run-of-the-mill anime arena fighter that never picked up any momentum. Doesn't help that it was compared unfavorably with the still-booming popularity of Dragon Ball Fighter Z.
• Unexpected Character:
  • The inclusion of Vaccine Man as a playable character took a lot of people by surprise considering how in canon, he only exists to introduce Saitama, and is never so much as mentioned again after his death.
  • Tanktop Black Hole was also unexpected: he only appeared in one scene, not to mention the largely-similar Tanktop Tiger and Tanktop Master are also in the game already.