With that in mind I've ignored the whole lot of them and gone back almost a decade to enjoy 2003's release from Goto80 - a Swedish chiptune musician who works primarily with the Commodore 64 computer (my own personal favourite). Although listed as a 2005 release in his discography, Goto80's cover of Wham!'s 'Last Christmas' was included on the 2003 compilation 'The 8bits of Christmas' from 8bitpeoples, a collection of eight Christmas songs created by artists on a variety of different classic machines (NES, GameBoy, Spectrum, VIC20, etc.).
I've chosen to highlight Goto80's song because it not only gets my nostalgic juices flowing for the Commodore 64, and I also happen to quite like the Wham! original anyway, but because it's a pretty good cover version within the chosen medium. Naturally - considering the limitations of the equipment used - there are no vocals, but the tune progresses nicely from a relatively simple interpretation of the chorus before introducing different elements to vary and fill out the sound. The verses are mostly ignored, but I think that was the right decision to take in this case where voice cannot be included.
All in all, this is an enjoyable and festive song from a highly regarded composer within the chiptune scene and well worth a listen by anyone with a hankering for something a little retro.
"Pop music is aspirin and the blues are vitamins" - Peter Tork