The legs of a game depends on so many things other than hardcore vs casual... For example, the guy who only knows 2 games, GTA and PES, know when the 2 games he plays will be released and buy them on day one. Can you say that someone who plays 2 games in his life is a hardcore gamer ?

I think the most important thing to determine legs is established franchise. That's what makes people buy games without having ever tried them. Then there's advertisement. If a game is worth a TV spot, people will think it's worth buying.

People buy stuff because they know about it, and because they know they'll like it.

That leads us to a simple "casual" equation :

The more a game sells, the more casual it is.

@ oyvoyvoyv - i think the biggest flaw in this analysis is the timing. for instance: i bought twillight princess 6 months after it's release not because i'm causal but because i couldn't find a wii. the longer the console is out the less stupid factors like this will matter cause you'll be able to use a larger sample size.

feel up to doing this analysis for ps2, xbox, and gc? i'd be interested in those results especially an estimate of casuals on the ps2.

^ The problem is that we don't have a lot of good weekly data for PS2/GC/Xbox games, so it's hard to know for sure what the legs were like. You can do a few in certain territories, like GTA:SA in NA, but the data isn't complete enough to do a full out analysis.

Hmm. I could do Japan only, perhaps. And make it 150 weeks. That wouldn't work out very well for overall though.

DQ8:
10 Weeks 3.4M
Lifetime: 3.6M

FFX:
10 weeks: 2.4M
Lifetime: 2.7M

FFXII
10 weeks: 2.3M
Lifetime: 2.4M

You see? Japan is way too hardcore, or Vgchartz is too guesstimated, for this to work.

Fun fact: Ps2 had 18 million sellers in Japan, Wii already has 5.

^ The other problem with that (though it's easy to correct) is that the graphs actually end before they reach the total sales... but that also might mean the graphcs aren't 100% correct. FFX in Japan, for instance, sold 3 million, not 2.7 million.