Do you ever buy games on impulse? Impulse meaning in this context that you didn't plan to buy the game in advance, but you saw it for sale somewhere and just had to get it. Interestingly, a recent study in Canada found that about 40% of the games sales in that country come from this kind of purchase.
I do this on occasion, but usually only if I find a game used or on clearance for a really great price. I won't spend $30+ on an impulse buy, $10 or less is something I might do.