AA member neotokeo2001 has done some hacks of three Atari 2600 games to give them a Christmas flavor. Here are those three games (downloads below).
Donkey Kong Christmas
(http://i1303.photobucket.com/albums/ag160/TrekMD/RVG%20Images/DK%20Xmas%201_zpsiupuhet4.png)
(http://i1303.photobucket.com/albums/ag160/TrekMD/RVG%20Images/DK%20Xmas%202_zpsx1e2xep2.png)
Donkey Kong Christmas (http://atariage.com/forums/topic/260090-donkey-kong-christmas/)
Bad Elf
(http://i1303.photobucket.com/albums/ag160/TrekMD/RVG%20Images/Bad%20Elf_zps7sjddjnp.png)
Bad Elf (Keystone Capers Christmas) (http://atariage.com/forums/topic/260118-bad-elf-keystone-capers-christmas/)
Santa Falls
(http://i1303.photobucket.com/albums/ag160/TrekMD/RVG%20Images/Santa%20Falls_zpsbozeyykw.png)
Santa Falls (Pitfall Christmas) (http://atariage.com/forums/topic/260112-santa-falls-pitfall-christmas/#entry3652903)