As of now, a seamless, "drop-in, drop-out" campaign co-op mod for Shadow of War does not exist. Unlike games with dedicated modding engines like Skyrim (Skyrim Together) or Elden Ring (Seamless Co-op), Shadow of War uses the proprietary Firebird engine. This engine is notoriously difficult to mod for networking, as it was never built to synchronize two player entities, world states, and the complex Nemesis System hierarchy simultaneously. Why a Co-op Mod is Difficult to Build
The "Saviour" mechanic takes on a literal meaning when your real-world friend leaps from a tower to parry a killing blow meant for you. Strategic Domination: middle-earth shadow of war multiplayer co-op mod
A betrayed Orc famously appears later, shaming the player. "You left me to die, Ranger!" But in co-op, who did the betraying? The mechanic loses narrative potency. As of now, a seamless, "drop-in, drop-out" campaign