Developer 2D Boy has branded a week-long ‘pay what you want’ promotion for PC and WiiWare title World Of Goo "a huge success” after the game sold 57,000 copies at an average price of $2.03.

The promotion saw sales of the game on Steam up 40 per cent week-on-week, while WiiWare sales rose nine per cent. 2D Boy said that the amount people were willing to pay for the game went up as the days went by before levelling off.

The San Francisco-based indie developer said that a significant percentage of the average price paid for the game went to PayPal for transaction fees, with 2D Boy ending up paying over 13 per cent in transaction fees due to the way PayPal fees are structured. For all purchases of around 30 cents and under, the developer saw no money.

2D Boy had initially planned to run the “experiment” for one week to celebrate World Of Goo’s first birthday, but due to the success of the promotion it has now been extended until October 25.

“This is just one data point about how this kind of pricing methodology can work, and we would need other developers to try it with different games and under different circumstances in order to be able to draw any real conclusions,” 2D Boy's Ron Carmel blogged. “One thing we can say for sure, is that a large reason this experiment generated so many sales, is the huge amount of press and blog coverage it got."

2D Boy has also revealed the results of a survey that canvassed gamers on how much they paid for the title, how they chose the price that they paid, and how much they thought the game was actually worth.

“One thing that the survey data might suggest is that despite there being a lot discussion around what games are worth and the dollar value of an hour of play, few people chose their price based on the perceived value of the game,” said Carmel. “How much the person feels they can afford seems to play a much larger role in the decision than how much the game is worth.”