A host of highly regarded apps for iPhone and iPad have gone free today in what could be a major celebration to mark five years since Apple launched the App Store. So far, games such as Infinity Blade II, Superbrothers: Sword and Sworcery EP, Where's My Water?, Badland and Tiny Wings (iPhone / iPad) are all on offer for nothing, alongside apps such as the beautiful photo-annotating app Over, Traktor DJ (iPhone / iPad), Day One, Over, How to Cook Everything, and Barefoot World Atlas.

Traktor DJ is normally $19.99

None of these apps have ever been free on the App Store before, and many have commanded relatively high prices until now. In the case of Traktor DJ for iPad, the app normally sells for $19.99, and comes recommended by The Verge's Nilay Patel and Trent Wolbe.

Apple is yet to make any announcement regarding the offers, and none of the apps in question give any explanation on their store pages. Since the App Store went live five years ago this week, the deals may be part of a coordinated celebration. The Verge has contacted Apple for more information on the matter.

Update: According to ABC News, the CEO of Touch Press (who makes Barefoot World Atlas) confirmed that the app going free is for a fifth-anniversary promotion. "Barefoot World Atlas went free this morning and will remain so all this week to help celebrate five years of the App Store," said CEO Max Whitby. "Today's promotion is another step down the road to help spread the word [about our apps]."

Whitby also indicated that the companies making their apps free were not being compensated by Apple for the loss of revenue. "In marketing apps you have to consider the big picture. The loss of one week's paid sales is far outweighed by the wider gain in awareness."