Set 48 years before the main events of the show, Beyond the Wall is set at (you guessed it) the Wall. And beyond it. You control the Lord Commander of the Night’s Watch as you recruit troops, reinforce Castle Black, and send out scouting parties to find out what happened to Bryden Rivers - the former Lord Commander, now missing beyond the Wall, and destined to end up as the Three-Eyed Raven.

That gives Beyond the Wall the space to tell its own story, one so far only thinly sketched by Martin or the team at HBO.

Still, don’t expect the game to offer too meaty a narrative. Creative Director Daniel Guertin explained that the average player should run through the six chapters within a couple of hours, though the open-ended finale will leave space for the devs to expand on it in future updates.

The big question mark right now is whether developers Behaviour Interactive (best known for horror sim Dead by Daylight, also getting a free-to-play mobile version next month) can balance their own story with what they admit is a vision “to create a fan service game.”

The most obvious way that plays out is in the inclusion of fan favourite characters like Jon Snow and Daenerys - even in a story set decades before either was born. They’re just some of the Hero units that can lead your forces into battle, and there is at least an in-universe excuse for including them here: the Three-Eyed Raven’s ‘Greensight’ can perceive events in different time periods.

That’s all the excuse the devs needed to include Jon and Daenerys - along with Melisandre, Tormund, and Jaime - who are playable in various encounters, including recreations of a couple of their own pivotal experiences, such as Jon’s first fight with a Wight, here dubbed Legendary Events.

Leaning on fan-favourite characters might detract slightly from Beyond the Wall’s emphasis on its original story, but it makes business sense. As a free-to-play title it’ll rely on people paying for characters to use in its various non-story modes (both multiplayer and single-player), and no doubt people want to pay to play as the people they know.

Factor in House of the Dragon and it makes even more sense. HBO’s next small-screen series in the Game of Thrones universe will itself be a prequel, and if Beyond the Wall is still a going concern by the time the next show arrives, there’s nothing to stop the devs from tying in with characters from that series too - something that Guertin admitted is a possibility, while carefully shying away from any specifics.

Still, the House of the Dragon is a ways off, and the Wall needs defending now. Game of Thrones: Beyond the Wall is out on iPhone and iPad from this Thursday 26 March, with an Android release to follow in April.