Here's the game I made for Drunken Coders' Second Annual Christmas Game Coding Competition
It's called Christmas Factory ,more infos on the link !
Couldn't test FPS online, here are my favourite entries (including mine :-p ) :
#1 : Clem, the retarderd Elf
#2 : The Sounds of Season
#3 : Rudolph
#4 : Christmas Factory
#5 : Santa's Skidoo
If you find that some great games are not here, I'm judging the theme related features, putting just a "winter gfx" isn't enough for me (don't ask which games I'm talking about, or I'll say it :-p ). Something else, this is just my opinion, and no-one should really cares...