'12 Days of Christmas (Video Game Music Edition)'

Great little idea perhaps run a quiz with it, answers on a postcard please, Lol

may2day, you absolute genius! This is one of the greatest mashup-type songs I've ever heard. So cleverly done! Filled me with joy.
I couldn't identity every theme, but I got most of them (maybe I'll list them in a reply to avoid openly posting spoilers).