I think you guys are spending way too much time on this. The big games, the GTA IV, the Devil May Cry 4's, the Halo 3's, all the games have huge advertising budgets. As such, the casual gamer is likely to see a commercial on TV, say hmm, I think that looks good and go out and buy the game within the first 10 weeks.
The biggest misconception is that hardcore is willing to invest lots of money but casuals aren't. Time for my personal experience analysis :). I am what I consider a hardcore game. I buy 30-40 games a year. However, 90% of them are used, and 80% of them I'll resell after I've had my share. As such, I'm not really putting much money into the gaming industry or really spending that much on games as I offset my purchases by selling games.
Is a casual person going to buy their 3-5 games a year used? Most likely not, because it would be too much trouble for them they would rather just walk into a store and get their fix. In fact, my brother in law took back Super Mario Galaxy because he didn't think he would have enough time for it. Can it get any more casual? But, when he saw me playing Guitar Hero and got a chance to play, he loved it. As such, he went out and bought two copies of Guitar Hero 3 for the Wii ($180 for one game) since there weren't stand alone guitars. And he bought them within the 10 week hardcore window.
In conclusion, I don't think the 10 week arbitrary time period works to break it out. I think it's much harder to break out the differences because casuals will spend the money if they are interested.
So a casual see's a Devil May Cry 4 commercial and runs out and buys it. Myself, I see the commercial and think I'd like to try that out, but I know the game won't be discontinued, I know the game will eventually go on sale, I can wait. I have mounds of games I need to beat already. As such, I'm much more unlikely to pick it up within the 10 week window. People like new things. I do pick up my high profile games within the 10 week window, but a casual is likely to pick up a game when they know of it, which is at launch for most of the big titles.
