The Holiday 2015 skin has been disabled and the game sprites have returned to their regular appearance.
The Holiday 2015 achievements have been set to "Hidden" and can no longer be unlocked in the present build of the game.
The new Holiday 2015 bonus tracks will remain on the Soundtrack DLC indefinitely.
In the next few days we will be putting the Holiday Skin build back out as free DLC. The Holiday 2015 achievements will be unlockable by playing this free DLC.