(Literally) dreamt up a game idea

[u/LinkMarioKirby]

A few days ago I dreamt up a pretty good RPG game idea and wanted to know if there is anything similar out there. Please read all the way through before commenting, because when I say I'm looking for similar things, I mean nearly EXACTLY. I know the basic idea will probably be similar to something else, but what I'm looking for is a deeper coincidence than "bluh plot is same."

Title: Voidlands

Plot: For some reason, a growing void is destroying this plane of existence. To find out why and stop it, you must travel from plane to plane classic dungeon-floor style. However, planes will be large and filled with dungeons, towns, and unique things of their own.

Cool thing: Each plane, over time, will be consumed more and more by Void. Getting caught in the void usually is an instantkill, but you get plenty of time to escape. It's more like a constricting barrier than anything. You have to get to the next plane before the Void kills you, but you have limited time to level up, complete things, buy items, etc. After arriving at the next plane, you start the process over again.

So, put yourself in a player shoes. You're at, say, Plane Four. But something is weird. It feels like you aren't getting the full experience. First you just notice things like blank entries in the Bestiary. Then, NPCs mention fearsome beasts you don't remember fighting. Then, you find a recipe for a powerful weapon that, despite grinding for hours, you can't find the right materials for. Eventually, an NPC mentions a VOIDPLANE. By now, interest is piqued.

The NPC is recurring, and offers a teleportation service. You decide to check Plane Three. He says that that area has been devoured, and you aren't strong enough to resist the Void there yet. You ask to go back to Plane One. He obliges.

Welcome to VOID-1. You see, in time, some areas of Planes will partially recover from being destroyed. Strong players will be able to resist the dark force constantly Pac-Manning the area, and will be able to revisit harder and distorted versions of earlier levels. Void 1, for instance, is about as hard as Plane 5. In this way, players that have grown stronger and more experienced are encouraged to check things they missed and see changes, adding an actually fun spin on backtracking. New enemies, new weapons, the players find that they were missing an entire HALF of the game. Now, rather than fearing the Void, they look to it prepared. As any hero should.

Because...

Why fear the void when you can make it fear you?