The longest game I ever created I would say takes 5-10 minutes to complete (4 months of development) but I’m pretty new to game development. Which game are you talking about because for me what is considered “too long” depends on the game. If this is a story based game where it’s a story and you choose a series of actions to alter the story, I would say aim for 10-20 minutes. If it’s any longer separate them into episodes/chapters.

If that 10-14 hours is playing time and not development time, then I would say it’s too long for a story based game. If I was playing a game like that I’d want to complete one full episode in one sitting. But splitting into different episodes/chapters should fix that problem.

It's hard to say. For games without save feature, 2 hours is long enough. But for ones with save features, I could play for 10 hours or more.

The question would be is the game compelling enough to play? and if it is, are there any new stuffs to discover for playing more?

If the answer to any question is no, player would start feeling the game is too long.

10 to 14 hours is a good length for a game with a strong narrative. I think it's not too long for a game on itch.

My games tends to be short but that also depends on player skills.

14 hours isn’t too long. I’ve played lots of games longer than that that didn’t feel too long. I think I’ve written games longer than that.

A better question is, does the game have good pacing? Does the plot keep moving forward? Does the game keep introducing new elements? And just as importantly, does it have downtime where you can think about one big event before introducing the next one? If the pacing feels right, then the game is the length it needs to be, whether that’s 10 minutes or 100 hours. If the pacing is off, the 10 minute game can feel too long and the 100 hour game can feel too short.

BEFORE I PLAY YOUR GAME:

I am assuming it is this, Nightmare in San Vicente, correct?

Before playing it, I will say this: itch.io - the administration and website - wants itch.io to be a "real" store. So, for them, there is no such thing as "too long."

Since you said in one of your devlogs that you wanted to eventually release a downloadable paid version, 14 hours is not a bad length. It may even help people think they are getting their money's worth.

To be honest, rather than focusing on length (I make long games), I think the most important thing is that the game be replayable—that is, different endings or variations on the ending, different builds, decisions that change the plot, etc. (you'll know what to do)

I think there's a big difference between telling a player... “The game lasts this long,”

and telling them... “You can play the game up to X times and you won't get bored.”

There's just no comparison—the second option is much better!