#1 Steam Sales.
Steam sales are by far the most effective way publishers and retailers get you to purchase games you don’t want. While Steam has had a monopoly on the sales for a few years, online retailers like Green Man Gaming and Amazon have upped the ante by beating Steam’s own sale prices with games that function perfectly well on Steam.
Their wiles aside, it’s hard to pass up a 75% discount on a game you’ll never even play, because you just like seeing it in your Steam library in case you ever find time away from Black Ops 2 or whatever it is you’re playing to try something different. You’ll play it for two hours—tops. Besides, you’ll tell yourself that you’ll feel like a schmuck for not picking the game up when it was on sale if and when the urge to play it ever comes around.
It’s a lose-lose proposition, because you’re going to feel like a sucker for buying the game anyway, since you’ll never actually play it.