It doesn't only has to do with raw length, it also has to do with pacing. The best example is chapter 4 of Witcher 1. The game at this point took a break from what it was building up, we got a whole new scenario with a radically different tone, much more peaceful and calm. It also set up a whole new array of interesting quests.
Perhaps if the game had continued on a scenario similar to chapter 2/3, then the game would have become tedious fast, but this design choice made it cool, I think.
So that's something to add to your analysis, its not just about how many hours the game has before it becomes tedious, its also what is in those hours (how much variety) and how its paced.
phroggie: I've been thinking about the notion of what is a good length for a game.
I've also got a PS3 and I definitely don't have as much time to spend on games I'd like to (and you could easily argue what I do spend is already to much!!!) ... so I really really love the games that clock in around 10-12 hours, the story is thick and solid without filler, if the game is that good there's a chance I can play it again. Perfectly surmised in PS3 games God of War III, Uncharted 2, Batman: Arkham Asylum and on the PC Starcraft 2 and Witcher 2 (which really took me 20ish hours first time).
I still have games I absolutely love sitting on my shelf that I've never finished and don't get a chance to get back to ... Neverwinter Nights 2 (and all expansions), Civilization V, Titan Quest, Demon's Souls and Dragon Age: Origins (which to be honest I don't like that much, might have prefered it more on the PC rather than PS3, I much rather NWN2). It took me over 6 months to get through Witcher 1 and there was no way I was going to replay for the different path, I loved it but the final third of the game I was racing through just to get to the conclusion.
So it got me thinking, is the 10-15 hour point a kind of critical space where story telling and action can go no further without repetition and boredom? For me, I cannot think of a single game I have ever played 20+ hours that completely held my attention.
Yes I want the story of The Witcher 2 to go on, but rather than expand the size of the current chapters with larger areas to cover and more quests that don't impact the story arc, I want the next full bodied chapters... but even if that story did continue after Chapter 3 I don't think the game could have possibly avoided some levels of tedium. I need a break from the journey, and I need the whole landscape, and possibly game mechanics to change or be upgraded.
I do want more of this fantastic world - but I never want the quality and depth of it to drop. And I don't think any development studio could have done that by expanding the games length. I think most other games above this game time have been lesser for it.
What do you think?