Here is what I've done so far. Not that impressive, but that's about 3 hours' work so I estimate at around 144 hours for the finished product. That's not counting the first and last squares for the title that I haven't designed yet!
For those that want it, here's a dropbox link to a hi-res version of the whole pattern that cross stitch designer spat out. Again, I don't have the names of the colours as I just judged them by eye and what I have in my thread box. if you want to be more specific you can probably find a lot of the true sprite colours online by googling around but I don't really have time for all that.
https://www.dropbox.com/s/5efeeobi46tu3ti/alphabet.jpg
The eagle-eyed amongst you may realise I've already made a slight mistake in that the left hand side of the B is too thin. When I realised it was too late to go back and unpick it all, but I'm hoping it won't be that noticeable in the end (crosses fingers!)
As usual all questions/comments welcome!