Multiplayer/Co-Op & Frictional Games? NO!!!

[Bek]

What about something like an "AI Director"?

Say the second 'player' can fly through the map, observing your progress, trigger events, spawn monsters, play with physics objects, toggle lights... it would add more randomness to it, if it was overdone though you'd get used to the idea that it's someone controlling everything. Of course there would have to be some limit to this to make sure they won't just be a dick and spawn 5000 chairs in between you and where you need to be.

Can't help but think it wouldn't work unless the person thought they were playing SP. An idea anyway.