The only issue I see with this is that the Guardian is a canonical character who did not exist before the events of Vanilla D1. Would you propose we play as specific characters using specific “builds” (currently within the game) and loadouts. Say, for the battle of Six Fronts, we play as Shaxx, and as a result, we use the Mountain Top and any of the abilities and powers he would have used in that battle (even if the player does not currently own the Mountain Top or the respective abilities) Honestly, these “Timeline Missions” could be a way to earn dedicated rewards like the Mountain Top and give Bungie a way to create curated and unique experiences that they would otherwise be remiss to adding to the greater game. All that being said, these Timeline missions would need to take place before the Guardian Exists, otherwise it would be a really weird experience for the players. It would be cool thought to say, play as Ikora during the Fall of the Last City back in Red War and have a cutscene where we see the Guardian Run by and Ikora gives them a command (in allusion to that specific moment in the First Mission)