Microsoft has loved teasing fans with clues about upcoming additions to the Xbox Game Pass subscription service. The most recent example saw the Xbox Game Pass Twitter account share a fake internal email which contained "absolutely no hints". Except of course the words, “The Slayer is Coming” hidden within the email text. This lead to speculation and then the announcement that Doom Eternal would be hitting the service.The latest clue, revealed over the weekend, is slightly less subtle than the last. It once again came courtesy of the Xbox Game Pass Twitter account, which simply tweeted an image of a castle under siege, with six rainbows arching over it. This is of course in reference to the fact that Ubisoft's Rainbow Six Siege is very likely to be hitting the service soon.

If this happens, it's another great get for Microsoft and Xbox Game Pass. In the lead up to the launch of both the PS5 and Xbox Series S and Series X, Ubisoft has confirmed that they are aiming for Rainbow Six Siege to hit 4K resolution and 120 frames per second. While players who have purchased the game on either the PS4 or Xbox One will get access to the next-gen upgrades for free, the Xbox Game Pass addition will be a great chance for players to dip their toes in who have yet to purchase it.

Tom Clancy's Rainbow Six Siege originally launched back in 2015 and over the five years since release has received continuous updates. The game recently entered year 5 season 3 and added new weapons, attachments and Splinter Cell's Sam Fisher. Siege is one of the biggest eSports games in the world with four leagues, a huge array of teams and a world cup competition.

Rainbow Six Siege is available now on PC, PS4 and Xbox One.