Apart from a few games, I think a majority of the ratings for the games here are good. I agree that 2* is probably the average, because I think most companies put out a game where most people don't have trouble finishing the game and getting all trophies/achievements. A 3* game would be a step up in either difficulty/time consumption, with a 4* being incredibly tough or time consuming, and 5* being a huge PITA to achieve platinum (a lot of games in this category are either "break your controller" frustrating or months of constant playing to achieve platinum, like WKC or Star Ocean 4). Personally, this is how I see it (don't forget that certain people have skills that may make a game easier to them)...
1* - A game that takes absolutely no skill to achieve platinum and can usually be gotten in 1-2 days
2* - A game that takes a little bit/some moderation of skill and/or takes a decent amount of time to complete (30-50 hours?)
3* - A game that has moderate difficulty, meaning it takes quite a bit of skill to complete. It can also mean a game takes a fair amount of time to finish (70-130 hours?)
4* - A game that takes a lot of skill to finish, or one that takes a long time to finish (175-250 hours?)
5* - A game that either takes master-like skill to complete (Ninja Gaiden Sigma 2) or an UNGODLY amount of time to finish (White Knight Chronicles; so around 350+ hours?)
Don't forget that a game can be really hard to complete, even if it takes 25-30 hours to finish, which might put it at 3 or 4*. Also, I emphasize in the above paragraph that a game that takes A LOT of hours to finish, but doesn't require you to actually be there to play it (like Mortal Kombat or Wizardry: Labyrinth of Lost Souls), so time shouldn't factor in much there.
Time should definitely be a factor if you're playing that entire time, as it's distracting you from playing other games. A 400 hour game would take 17 days to complete, if you were playing 24 hours each day (which is not going to happen). At 12 hours a day, which is something a little more realistic for some people, that comes out to 34 days, which means you would probably be spending one month and one week playing nothing but the same game.
