It depends on the specific situation and the character's personality. Some heroes might have moments of fear but overcome them through their determination and sense of duty.
The MHA game doesn't necessarily spoil the manga. It might reference elements from it, but whether it spoils it really depends on how familiar you are with the manga and how much new information the game presents that you haven't come across in the manga yet.
Well, in the MHA manga, Dabi does meet his end. It's a poignant moment that has significant implications for the story's progression and the dynamics among the characters.