A little light thought and a quick post to look at holidays in gaming.
I think all of us have tapped into the holiday vibe either directly or indirectly in our games. Whether it's a scenario that directly involves a specific holiday or something that simply taps into the vibe of the season games can benefit greatly from some holiday coating. How you go about depends on the intended effect.
In these sorts of games, the character/players are involved in the activities or folklore of the holiday. The holiday is not just a backdrop for the story, but is a good part of the story. Characters can be helping a holiday spirit accomplish its task, or are making sure that the local holiday is observed properly.
Examples of this would be delivering gifts for Santa, saving Santa from evil-doers, making sure the mid-winter hobgoblin is sufficiently bribed so that he will not interrupt the festivities. Whatever it is, the players and their characters will have some direct effect on the holiday.
What can I say? This is every Die Hard movie. The characters are undertaking action using the holiday as window dressing and/or a story factor. If the holiday is a factor in the events of the story it's usually in providing suitable obstacles to the adventure or game. Limited availability of help, local closures of services, or even limited movement due to the environment at that time of year. Perhaps the players have a time commitment and have to be home for the parade of the Elf King and his winter court.
This particular method is really a good way to establish character in a fantasy world. Holidays speak volumes about their parent cultures and you can get a lot of mileage out of featuring a holiday observance in your RPG campaign.
The holiday doesn't have to play into this at all, but the adventure evokes the feel or themes of a holiday. This is popular among gamers who like to run spooky horror games coinciding with Halloween, but could tap into other holidays. Superhero themed games are easy for this as you can have villains with holiday motifs and all sorts of holiday-inspired villainy.