there is a fan made christmas metal gear game and you should try it!
i was looking for christmas cards from metal gear social and instead found the fan made game merry gear solid: secret santa. it is available for free and only takes ~15 minutes to complete, has cool voice acting, funny codec calls, simple controls (arrows, shift, control and mouse) and few fun mechanics like candy cane instead of cigs, gift box (full of bombs!) and a (non digital) camera that is like stun grenade x claymore x c4. in this game, you are playing as santa claus (code name solid santa) and due to tightened security have to infiltrate the house to deliver presents instead of the traditional way. of course, a plot twist awaits at the end, and an even bigger one in the after credits call!
please give it a try, download available at http://www.superfundungeonrun.com/?page_id=297 . you can also look up walkthrough on youtube but why rid yourself of the experience of playing it yourself? i have read the plot summary before playing it and spoiled everything but still had a lot of fun, and hope that you will too!
there is a sequel that i want to play as well!