There's you... and well, that's just about it...
From the introduction:
If you never dreamt yourself alone in the world, if you never fantasized about the stripping away of the rest of human kind, this game may shock you. On the other hand, if you never had those thoughts, the experience of playing Apocalyze will be that much more acute to you.
The game requires three players; one game master and two "sole" survivors who possibly meet, but only after concluding they are the last person alive.