I remember that Serious Sam Second Encounter (classic version) has a Serious Santa Claus in a level of the solo campaign. Shoot him to grab some items ;)

Really? Far out! XD
Leave it to Sam to go the extra mile. When Santa shows up in Duke you have to save him for items, with Sam you have to shoot him. :P

Nah, too busy with my own version of It's A Wonderful Life. Kanon marathon (check anidb.net for both series).

I like Christmas - themed games & replay some fun casual ones every year.

I haven't seen our old 3.5's with Holidays Lemmings in a lot of years though.
I wish GoG had the Lemmings games in their catalog. Ah well, one of these days, I hope!

Have there been any other decent xmas themed games aside from that said lemmings games?

Yeah, for many years now I am trying to finish Quake with all expansions. Don't even ask why I cant do that :) Besides that I would like to finish Shadow Warrior and also Shadow Warrior Classic Redux I just bought. Also I started Dungeon Keeper.

I want to finish some games that are full HD and delete them from HDD since I need to get my monitor to guarantee service and for replacement I only have some old 17" CRT which is also kind of broken by the way. And in this country it make take some time since they are cheating as they can, and don't fix or replace the hardware as long as they can... Last year I waited half a year for replace of a broken pendrive...