I'll suggest something.
Don't make chapters too short. Divide them in parts.
Really. If you don't divide them in parts, you'll end up with like, hundreds of chapters if the story is long. However, if the story isn't actually THAT long, you can make every part a chapter. And that leads to my other suggestion.
Don't make parts too short.
Really, add something of interest! A sub-plot, you know, stuff like that. A short part is NOT interesting. Really, the world of stories is also the world of fan-fiction. You can add something not normally seen in the game/series (Like a Waddle Dee with a sword), however, don't exaggerate much (I mean, don't go like "Sonic suddenly appeared from a block Mario hit", but you COULD make that if it's a Mario and Sonic crossover story, but you should edit it so it says something like "Sonic suddenly appeared from the Giant robot Mario had beaten.". The point is, don't make it too weird)









