Infinity Blade 2 was given away free of charge on the App Store last week in celebration of the store's fifth birthday and, according to Chair Entertainment publicist Laura Mustard, shifted 5.7 million copies during the seven days of the promotion alone.

1.7 million of them came during the first day.

Infinity Blade 2 offers in-app purchases to bolster its income, something which could generate significant revenue when there are 5.7 million new players. However, Chair doesn't place too much importance on in-app purchases.

"While we normally notice an increase at times when we've done free promotions, we don't think it's significant, because the game is balanced in a way that does not require any IAP,"" explained Mustard.

The Infinity Blade 2 offer had a positive knock-on affect on the first game, which sold 2.5 times what it achieved in the week prior.

All Things D reports that the two games combined have now sold almost 50 million copies.

Source: All Things D