I have noticed that with the latest update of temple run 2, there is a new challenge called artifacts that has appeared. They seem to appear in chests. You acquire them just like other bonus items and they seem to come in random order and time. I have also noticed that you can acquire more than one of the same artifacts. You only know what the artifacts are after the games has been completed. All of them, yet, are rings (infinite loop ring - which I have acquired twice). Is there a comprehensive list of artifacts and Is there some expectation of when I can acquire all of them?
I collected all 10 artifacts & after that nothing happens. The objective to collect them all is done and there's no other objectives & still at level 9. So disappointing. Just letting you know. Here's a list of all 10 ring artifacts: Infinite Loop, Angel Wings, Twisted Root, Floating Island, Sky Clasp, Demon Claw, Ruby Shard, Caves Maw, Mystic Rocks & Idol's Curse.
In addition, here is a list of the Christmas-themed artifacts added in the December 2013 update: a candy cane, present, wreath, stocking, and a piece of holly. Once you collect all of Christmas artifacts, your character gets to wear a Christmas hat, and you can play as Santa for 60 gems.
Further addition: there are 5 Valentine's day related artifacts available in chests in a recent update as well.