The official Fallout Twitter account have announced that players can get into the festive spirit with the Fallout Shelter Holiday Update.
The update adds new decorations, outfits and quests which are available only for a limited amount of time.
— Fallout (@Fallout) December 20, 2016
Limited time quests like “Rescue Santa!” and “Santa’s Helpers” await for those over level 11. You can also pick up new gear like the Elf Suit (I+3, L+2) and an original Santa Suit (P+4, E+3, C+4). The outfits appear in the lunchboxes during the festive event, so if you have been saving them for the special occasion, now might be the time to crack them open.
Locations like the Cafeteria have undergone some festive decoration with Santa hats, snowflakes and mistletoe bringing that festive cheer to the shelter.