Back in the day, we sometimes called this "shareware". The first episode of Commander Keen was free, but episodes two and three cost money. :)<p>Or we called it a free trial, or a demo. We included a disc with a crippled version of the game in a video card box, or we glued it to the cover of a gaming magazine. Or we called the extra parts expansion packs. Or sequels. Or DLC. Or, yes, we sell them for real currency in an in-game item store as with Farmville (or League of Legends, World of Tanks, Gunbound, etc.)<p>All of it boils down to the same thing: Some people pay nothing and consume some amount of free content. Other people pay $X and get some higher amount of content, even while other people pay a higher $Y and get even more content. And still others will pay less, and get the same content, because they waited for a Steam sale.<p>And so it goes. Pick any six gamers at random who own Portal, and they all probably paid different amounts for it: Some bought it as part of the Orange Box, some individually, some got it for free, some bought it in a store, some got it for free when they bought Portal 2, some bought it on sale, some bought it after the price was cut, some bought it in the US, some bought it in various other countries, some bought it using USD, some bought it using a different currency. There's probably 500 different prices you <i>could</i> have paid for Portal. (Actually a lot more, once you include exchange rate fluctuations for people buying Steam games in USD using a non-USD currency.)<p>And you know what? Meh. There's not a lot new under the sun. (Especially when it comes to ways of relieving punters from their cash.)