In that case, I'd make it as long as I can...
Viewing post in When do you consider a game to be ‘too long’?
That’s what I did, and for a paid, downloadable game for Windows, it’s fine, but I think I should have split the web version into chapters. It also has a save option, but all the browser-based games I’ve seen are much shorter...
The game will have at least two more parts, but if they’re just as long, I think I’ll split them up... 🤷