The reward for completing the Frozen Artefacts in the new update

If you're aiming for a high score, you need to keep objectives in mind as well. Spending coins on upgrades and consumables (sans characters) nets you 5 objectives and another five multipliers on your high score:

• Used a resurrection
• All level 1 upgrades
• Used a head start
• Resurrected twice in one run
• All level 5 upgrades

All of these are easy and cheap except for the level 5 upgrade one, which you can tackle in the long term. Objectives and score do not affect coin gathering though.

If you know you're in the game for the long haul and you'll have all the objectives eventually, you probably want to focus on the Coin Values upgrade. You'll start getting double and triple coins much earlier in your runs which really add up in the long term. Boost is essentially a score-inflating upgrade as is invisibility - they don't improve your coin count alone, they'll just help you get farther. Coin magnet is useful if you're bad at tilting but otherwise can be left until later. Mega coin is a direct impact on your coin count but you still have to wait for it to show randomly in-game.

Strictly from an efficiency standpoint, I'd grab level one in mega coin, then max coin value before going back and forth between mega coin and coin magnet until they're maxed. Then focus on the other two and objectives to get the high scores.

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.