: It would probably be quite doable, but in the strictest sense, it might need
: at least some modification in order to work entirely correctly with more.
: There may very well be things that only make sense with exactly one or
: exactly two players.

: Halo 1 may be able to handle a third weapon if you trick the game into giving
: you the PoA pistol when you already have two guns, but not everything in
: all software in the world is implemented as magical linked lists and other
: expandable structures.

I would say something about that being bad practice or at least bad future-proofing, but your point remains.
While we're on these features, what about drop-in/drop-out co-op, or at least drop-out co-op like Reach and Halo 4 have? We'd all like that, right? Has anyone asked about it?