This is a randomizer of sorts for Final Fantasy 1. It essentially erases all the existing dungeon data and turns Coneria Castle into a procedurally generated 50-ish floor dungeon.

Every so many floors there will be a branch to the next town. You can save at the Inns in the towns, but when you load your game, you will be back on the overworld outside Coneria Castle.

Somewhere on the final floor will be Chaos. In addition, there is a Bahamut and a TAIL randomly placed somewhere in the dungeon; they may not be on the same floor, and they could be encountered in either order. In addition, there are four Ribbons distributed relatively randomly throughout the dungeon.

The treasures will on average get “better” the deeper you go into the dungeon, as do the “difficulty” of the monster encounters.

Since “shelter” items like TENT have no real purpose anymore, a patch has also been included that you can optionally apply to turn those items into Ethers. (The inn-related bugs with this patch have been fixed as of 1.7)

Deep Dungeon is mostly compatible with FFR’s convenience and bugfix patches, but using FFR will cause certain chests that contain gold to display as “In the chest, you found…” (nothing). This is cosmetic only, and the gold IS correctly added to your GP total.