'Twas the night before Christmas, and all through the house, not a creature was stirring, not even... Santa's Second World War-vintage self-propelled gun?
This is a Christmas greeting from Wargaming, developers of the amusing World of Tanks. So, yeah, the reindeer are out, replaced by tanks.
Few games or developers could pull this off without it looking stupid. Since World of Tanks is an MMO where you play as a tank, though, yeah, they can pull it off.