On the one-year anniversary of the product's release, the developers decided to undertake an e-commerce experiment. They offered to sell the game (previously retailing at $20) to anyone for whatever price the customer was willing to pay: "...one cent, a million dollars, the usual twenty, or any creative number they let you type into the text field."
In the week that followed, 57,000 additional people purchased the game; the graph above shows what prices they opted to pay. About 17,000 people paid $0.01, but another 16,000 paid $1.00-$1.99, and several hundred paid the full $20.00 original price. Total sales = over $100,000 for the week. And still rising, because they have announced that they are continuing the offer until October 25.
The developers discussion at their website includes their impressions of why people paid different amounts, and notes that they made no money when people paid less than $0.30 because of Paypal transaction costs. For further discussion of this odd marketing strategy, see Rock, Paper Shotgun.