The Forgotten Portal

Deep under the world, in the heart of every ancient city, stands a frame of reinforced deepslate. It is the right shape. It is the right size.

This mod lights it, and makes it the only door.

The Nether has to be found

Obsidian no longer opens anything in the Overworld. A bucket of lava and a flint and steel used to be the whole price of admission. Not any more. You can still build portals in the Nether, so you will always find your way out, but on the surface the trick is dead.

The city frame is the way in. Descend, survive whatever guards the place, and light the frame that has been waiting there all along. There is nothing to build. The structure is already there, twenty blocks wide and seven tall, exactly within what a Nether portal accepts.

And the Nether becomes a network between cities. Any portal you build down there drops you at the nearest ancient city, not back where you started. The frame lights itself as you step out, and it stays lit. Dig your portal near where you want to go, and you surface at the city closest to it. Ancient cities stop being isolated dungeons and become stations on a map you build by playing.

Why reinforced deepslate

Because you cannot get any. It has no drop, not even with Silk Touch, no recipe, and it shrugs off every explosion in the game. The only frame of that material in your entire world is the one Mojang already placed for you.

The gate cannot be cheated, because there is nothing to cheat with.

Adding this to a world you already play

Nothing you built breaks. Every portal already standing keeps working, keeps its link, and can still be taken down the normal way by breaking its frame. The mod refuses new obsidian portals in the Overworld; it does not go back and undo the ones you made before installing it.

The change lands the next time you try to light one.

What this changes about your world

Everything the Nether holds now sits behind a journey instead of a bucket. Blaze rods, quartz, ancient debris, and every potion that starts with nether wart are on the far side of a descent into the deep dark. That is the point. If you want the Nether to be a mid-game shortcut, this mod is not for you.

Compatibility

No new blocks, no new items, no changes to world generation. The mod changes what counts as a portal frame and where the Nether sends you back.

If you run another mod that redirects return portals, expect the two to argue.