Wow, THIS. I also do it and compare it to what I pay for cinema. I'm usually disappointed if a game offers me less than 3€/h (If I paid more than 3€ per hour). With a price of 60 for most games that would amount to a playtime of ~20h. As a RPG person I haven't often been dissapointed by the length of a game though :D

Short: -20 hours

Regular: 30 / 50 hours

Long: 70+ hours

to me at least xD

X-10 Very short
10-20 Short
20-30 Medium
30-40 Long
40-X Very long

The expectation depends on the game though. Ever since the incorporation of voice acting, elmination of CGI, cinematic camera work, etc. story has become shorter do to costs. I wouldn't expect an Uncharted game to go on for 40 hours because that would be really expensive to make and to be honest what would the story be about? The gameplay isn't that time consuming in that game either. A final fantasy, I expect a longer story but gameplay takes up a big chunk of those games, but then you have to incorporate side quests and stuff. A game shouldn't be so long that it is unbearable either. Didn't Xenosaga have over 20 hours of cuts scenes alone? And that game dragged on. Anything that takes more than 60 to 80 hours has to start askings itself what it is doing or it might be too late.

> 6: Anything less than 6 is too short even if it's really great. I loved Enslaved but it was too short for $60.

6-8: Short, but if it's all good than it's worth the purchase.

8-12: Medium length is fine. An eight hour story can be the perfect if the passing is right.

12-20: If the game has enough variety and the story is strong enough than the more the merrier. For example Tomb Raider never overstays it's welcome because it's so good that playing for 20 hours never gets old.

20+ Longer games can overstay their welcome. RPG can often go on for 100s of hours. Some fans love it. I prefer shorter adventures with more focus.

Depends on the genre. If an FPS has a campaign over 12 hours I consider it long. If an RPG has a campaign under 20 hours I consider it short.

Are you primarily an RPG player? I'd only expect length like that from RPGs. A FPS would have to be apsolutly killer to go on that long without overstaying it's welcome.

Most games that go below 20-25 hours aren't worth it. (Unless done right. Like most 2D Platformers.)
Anything above 30 Hours would be pretty good for most games.
Games like Pokemon, with 100's of hours of gameplay, are absolutely awesome. (I know this list wasn't exactly what you were looking for but... deal with it! It's hard to be specific about these types of things.)

As you can see, I don't really play FPS games as they are way, way too short and boring. (In my opinion, of course.)

Not RPG's

Short <10 hours,
Medium 10-15 Hours
Long 15+ hours

Granted this is a bit difficult because just adjusting the difficultly level in say uncharted, Tomb Raider, or Dead Space makes the game significantly longer. 

RPG's

<20 Short 
20-35 Medium
35+ Long

RPG's are difficult because Elder Scrolls for instance is really short, but gives you a ton of optional content and that's what you play it for. And some RPG's are longer but have a bunch of filler optional content.

It depends on the genre. I like my JRPGs to be at least 40 hours long. I think FPS campaigns should be no longer than 10. Strategy games should take hundreds of hours to get through. It's hard to generalize because different types of games should have different lengths.

Yeah but no, people say ''the main story'' but i actually (if the game lets you do so) don't go through the main story like an arrow looking for it's objective, when someone says main story i think to me sounds more like ''first playthough'' even if for you is something different, Saints Row 3 for example took me 41 hours, i know of some people who completed it in 12 w/o rushing, so it's more about my non linear playstyle and of course if the game lets you play like that, that's why i didn't like say God of War or Devil May Cry that much, what i call corridor games, because they are enjoyable but too short and you just have to do it that way, they force you through a path you get me? you just HAVE to because you have no other place to go, it's not about the genre because there are AA and TP Action games and even FPS's that are not that strict, those i like more ^^