Death is not the end of everything. As long as you have a strong enough obsession, you will be resurrected in another world.
Those who are obsessed with survival become players, struggling in one nightmare copy after another, seeking opportunities to resurrect in the old world.
Obsession for the dead becomes the shaper and controller of the nightmare copy, squeezing fear from the players, and constructing everything they can't ask for in the new world.
And Tristan is just an ordinary NPC.
Concept: Home is the gentlest harbor