I haven't touched a Gears game for probably ten years, but I noticed the talk about this promo online and so installed the Xbox app for the hell of it.
Thanks MS. I think I only ever played a couple of hours of UE back in the day, but I can't remember where as it isn't in my library. Maybe they went off my ancient gamerscore or something, where the first three games in the series were as finished on the 360.
Either way, I ain't complaining