Turtles all the way down

Imagine a multi-verse in which there are worlds / planes / places are linked by one-directional gateways. Anything can go through them in one direction, but nothing the other way. These gates and places form a graph that is acyclic - if you go from A to B, there is never a way of getting from B to A.

Travellers sometimes leave their home world and hop to a new one - but every hop is made completely blind because no one can ever return. The gateway at the end of the river could go to a paradise beyond imagining, or a burning maelstrom and a painful death - or it could just go to another place like the one you started from.

Enough travellers have taken this blind leap over the centuries that every world has stories of people who have travelled to here from worlds upstream. Which might mean that if you jump downstream there will be another world "below" you to go to. Or your world could just be the last one, and every gateway from here leads to death.

A game idea within this context: You control a character is who remarkable for one reason. When you die, the game loads back to the last checkpoint. Except, as you play, you realise this isn't just a video game convention, it is actually what the character experiences. You and your character alone have any memory of stepping through that gate. As far as everyone else is concerned it never happened.

Your character is unique in that they can get information from downstream, upstream.

We could apply this to solving puzzles with information from worlds that, as far as your travelling companions are concerned, you have never been to.

Also, what if the story is about an ordinary human from Earth who accidentally stumbles into a gate that leads him on a journey further and further away from home - until he realizes that he needs to kill himself at every level to bring himself back to the moment before he ever left Earth. At each level his companions try to stop him - how can they possibly believe he is not insane?

As an alternative to suicide, the condition for jumping up a level could just be a shock - the moment just before death, like waking from a dream. Which then leads to this question: If you wake up from it like a dream, no time has passed in the world next up the tree, and no one else has any memory it happening - has it actually happened? If you stayed in world B forever then it would be real, but as soon as you "wake up" it never happened. When our character finally finishes his quest and startles back into his life in our world, he will wonder - did it ever happen?

(Related to this post: Charles Stross's novel Glasshouse pictures a universe where FTL is accomplished via wormholes that break you down, transmit you as information, and then rebuild you at the other end. They have an insidious war where when you flee the warzone, the wormholes have been compromised and wipe all your memories of the war before beaming you away. So no one outside / after the war has any idea about what happened. Chilling book, but well worth a read.)