When I started making my demo, I imagined it as a short, enticing slice of the game. Something to hook players and leave them wanting more. But as development went on, I realized… my “slice” was turning into a full meal.

Right now, the first level alone can take 4–5 hours to finish for most players. A completionist could spend 12+ hours finding every item and tracking down every monster. And that’s just the demo.

Some developers swear that a demo should only last 20–40 minutes — enough to tease the mechanics and tone. Others say a longer demo can build a loyal fanbase if it’s fun and replayable.

For me, cutting content just doesn’t feel right. The flow of the level, the buildup of upgrades, and the reveal of rare monsters all rely on that longer playtime. I want players to feel invested by the end, not just curious.

I’m still wondering if it’s too much, but I also believe the real hook of my game isn’t just a short taste — it’s the full experience of hunting, surviving, and discovering secrets.

What do you think? Is a long demo a strength or a risk? Would you play one that could last 4–12 hours?

If you’re curious, you can try the demo here: https://mictoons.itch.io/ghosts-and-monsters

Suppose it depends on the length of the total game. Danganronpa V3's demo is an edited version of the 1st chapter that's about 1 1/2 hours long and that game takes 30-40 hours to complete but then again it depends on how your game is structured and how story heavy it is. Technically Deltarune chapter 1 and 2 is a demo (don't know about now but it was classed as a demo on steam) and that was about 5 hours in total. How long is the game's play time? How much story does it have? I think a demo shouldn't be any longer than 2 hours but if you have a long, story heavy game then that's a different situation.

My opinion is:

If one’s good with marketing and willing to put extra focus on it and convincing players to move from the large demo to the full game: A very large demo (almost the size of a game itself) is fine.

If marketing isn’t really one of the primary focuses: I’d probably keep it simple and not make the demo over 2-4 hours long.

How long should a demo be? Depends. A lot.

What purpose has the demo? What is the target audience? And since you post this here on Itch and you do not seem to be an established developer, nor have a finished game, what is the plan for publishing the game?

Why do people play demos? I would say, to try before buying. For games that were successfully advertised to them (or which they found by accident).

They are needed on Itch because there is no easy refund policy and because Itch does not advertise the game for you. And people are not gonna buy an unknown game from an unknown developer just like that.

But they also might not be the best choice of strategy for some games. The Itch crowd is used to pay what you want games and free stuff. If you only release on Itch, pay what you want is said to often result in more sales, but milage might vary greatly here. So instead of doing paid+demo, free+optional paid content might be the better strategy. 

My suggestion, also with the genre in mind, would be a public/free version of the game, instead of a demo version. And a paid deluxe version with more bells and whistles or whatever seems suitable. A web version might do the trick. If you want to see a very successful implementation of this, Backpack Hero comes to mind. Their public version is an earlier version of the game as a web build. They do not have a "demo" version of the game.

So. How long should a demo be, if a demo is what you wanna do.

For a roguelike game, do not limit it in "length". If you make a puzzle game, or some adventure maybe, you might limit the level / scenario you can reach. But roguelikes have that repeating dungeon dive mechanic. Players will expect to replay the game, not reach more difficult puzzles or later parts of the story. So a demo should give them a experience they want to repeat and replay. And in my opinion, it will be very hard to give that experience by limiting the "length" of the demo. Imagine playing Slay the Spire to the first boss as a demo vs. limiting the playable character. Which demo would work better? We will never know, because it has no demo that I would know of, as it was released in a way that can get away without having a demo.