What if the Infinite Forest had playable simulations from Humanity's history? Like Assassin's creed with a twist. You are an outisder within the simulation, so your very presence has changed things somewhat, but you get bits of lore as you interact with it.

Say there is a Golden Age macguffin that can stop the Vex's plans, but we don't know where it is in the modern timeline. You bounce from simulation to simulation throughout the golden age and collapse looking for it's final resting place. You see the traveler terraforming planets. You live through great battles from the Grimoire. You see Crota slay thousands of guardians. You see Osiris in his hey day, and his ouster from the Vanguard. Just as things start to get interesting within each simulation, the Vex zero in on your location within the Forest, and they start spawning into the simulation and attacking you.

Imagine being at the battle of Crota, and the vex show up, now you have simulated guardians, hive and vex all fighting each other, as you try to open a portal to jump to another simulation.

Before you say, "but Vex can't simulate Guardians or the Light....." the opening Osiris cinematic showed that they were simulating guardians. What if all the time Osiris spent in the system, wreaking havoc actually gave them enough data to approximate guardians?

Anyways, I was thinking that these simulated missions could be kinda like the Claptastic Voyage from Borderlands the Presequel, where you are playing inside simulated memories of Clap Trap. They aren't exact (b/c obviously you didn't exist in the original occurrence, yet you are in the simulation, so have therefore altered things), there are geometry errors due to corruption of the memory/simulation, but it gives you a glimpse into humanity's past, teases at things to come, and lets you experience some of the best stories from the destiny universe.