The best Game of Thrones game we are likely to get is a Mount & Blade: Warband mod according to Gamecrate.
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The sheer size and scope of A World of Ice and Fire is impressive on its own, but for a fan-based mod what’s really impressive is how dedicated the mod author Produno is to doing justice not just to the subject matter but to the grim, cut-throat tone we all know so well. It’s an attention to detail and difficulty that pays off by making you feel like you’re actively struggling to survive not just in a game, but in Westeros itself.
If you’re interested in diving into the mod yourself, it’s available on its Moddb page and the Steam Workshop.