I was an avid spriter and Nintendo fan since a young age, growing up with an NES in the house. Since then I've gained a healthy appreciation for all types of video games. I also happen to be an avid reader with a fondness for history, alt history, fantasy, and science fiction.
I wouldn't worry too much about length. The quality of the experience is, in my opinion, of more importance. If the game is a long boring slog, no one will like it. If the game is great, albeit short, it will still be a great game. May the players with there was more? Perhaps. Try to shoot for quality first and handle quantity later.