Definitely a Toon or supers game if the players are creating new characters.Also-rans save Christmas - Santa and Frosty and all the main holiday characters have been kidnapped. The players will play a team of second-string holiday characters (such as Good King Wenceslas, Godfather Drosselmeyer from The Nutcracker, Minty the Candy Cane that Fell On The Ground, Mr.Fezziwig, the Little Match Girl, or new original characters that they make up themselves; but any new characters shoukd be that level of tangential) assembled to save the main team. Possibly suitable for Toon.
Hey! What about making it into an adventure for the denizens of the Island of Misfit Toys?

Misfit Toys
The residents of the Island of Misfit Toys are a group of characters from the Rankin/Bass television special Rudolph the Red-Nosed Reindeer. They are sentient toys who all have some strange quirk about them. Because of said quirks, these toys feel that there is no human child who could possibly...