Am I the only one who thinks that the ever-changing structure of the Infinite Forest would lend itself amazingly well to a "Prison of Elders" style arena mode? There wouldn't even be the need to actually create much in the way of new environemnts. Rather, they could use existing battlefields within the Forest, with the player simply following triangle-shaped passages to each level (and being able to pause to change weapons in said passages, like the central room in PoE). The top of that structure where we face the Root Mind, the place with all the lasers where we fight that giant Cabal, the fighting ground in "Bug in the Machine", and even the generic structure of the forest's transit zone (the place where you face the daemons to open doors) could all make battlezones. And, we could face the simulated Vex, Fallen, Cabal, and Hive that are already there, as well as Taken and even Splicers. At the end of the journey, you take one last passage which has a treasure chest at the end; you loot it and then leave through the exit and are deposited back on Mercury. As for who narrates it, Osiris and Sagira could provide a running commentary (the interplay between them, and between Sagira and your Ghost, is a highlight of "Osiris"). Alternatively, Osiris could announce that "I've created a simulation of an old friend of yours", allowing Variks to return. New lines could be recorded, but D1 lines could also be recycled since this is a simulation; they could make this addition without any new dialogue being necessary at all; it would just be a matter of splicing Prison of Elders mechanics with environments they've already assembled. Not saying it wouldn't be difficult, but I think the return of horde mode to D2 would be worth the aggravation. Just a thought.