The Soul Forge: a single-level branch off Gehennom that contains a smith. The smith will take two items of the same type and forge them together into one; in technical terms this destroys one of them and imbues the other with whatever object properties the destroyed one had. They cannot both be artifacts, and if one is an artifact, it will not be the one destroyed, so the properties from the other one will be transferred to the artifact.

The smith’s price is based on how many object properties the resulting item will have, increased if it will be an artifact. In dNetHack, the smith would require payment in soul coins, but in variants without those, they may just ask for gold or some other valuable. If paid in soul coins, the requested type of coin would be random but deterministic based on the object IDs of the two items.

A new single-level “heaven” branch, reachable by levelporting to a negative level, that is filled with angels guarding the “Holy Scepter”, a new artifact with unspecified properties. There is an exit portal on the level, and the angelic guards are peaceful unless angered or the Scepter is taken. If you steal the Scepter, you can sacrifice it on Moloch’s high altar to get a bad ending to the game.

On the level below the Quest portal, there is another magic portal to part or a whole of another role’s Quest. Possibly this leaves off the home and goal levels, consisting of only the filler and locate levels, or only the locate level as a single-level branch, or else it removes the nemesis and artifact, removes the restriction on going past the home level, and gives the quest leader some insulting lines to offer to this competitor for the Amulet.

A couple quests for roles other than the hero’s are available to complete in the game, as extra side branches. These can be accessed from magic portals in Gehennom below the Valley of the Dead.

Add a side branch that can only be entered by dying in a certain place such as the Valley of the Dead, or by life saving not working. When you die, you appear there with no inventory and have to fight your way out to return to your body. Monsters are also subject to this and appear in that branch after dying to the same conditions. However, it only works once - if you die again you die for good, even if you successfully got back to your body in the process.

New branch named “The Ancient Library”. It is likely accessed by portal from the main dungeon rather than stairs. It contains some spellbooks and a smaller number of scrolls, which serve as the main loot of this branch, but there aren’t too many of them in order not to be unbalancing. The level design makes it still visibly a structure, but fairly ruined with collapsed walls and such.

The branch is populated by monsters of a new species that either serve as the guardians of the library, or have moved in to inhabit it after its decline. They make for a difficult fight, and compounding the problem, taking a book will awaken and anger all of them on the current level. (Or the books spawn embedded in the walls – bookshelves, and you need to kick the walls to get them out, which triggers this.) There is no singular boss monster in the branch, nor is there any singular reward item.

If bookworms (#1793) are implemented, they also appear in this branch.

Create a new branch that contains the player’s role’s first sacrifice gift at the end of it; their god will no longer grant that artifact as a gift. Roles currently without first sacrifice gifts must have artifacts created to take this place.

Split Gehennom into two different branches - Hell, which contains devils and the lawful “demon” lords like Asmodeus, and the Abyss, which contains demons and the chaotic demon lords. Either only one of these generates in a given game, or the player gets a choice of which one to go to in the Valley of the Dead. Alternatively, they’re sequential parts of Gehennom, with the Abyss being deeper.

Revamp Gehennom by making its main branch substantially shorter, a “hub” branch containing stairs or portals to a bunch of sub-branches containing demon lords’ lairs. Most of the lairs are optional, but at least some of them are required in order to enter the Sanctum. Each demon lord that you don’t kill, however, incurs a unique, harsh effect or debuff on you once you have the Amulet. Suggested ones include:

• The mysterious force, as it exists in vanilla.
• When you try to ascend the stairs, they vanish and several illusory copies of stairs appear across the level, along with one real one which you have to find.
• Walls extrude from existing walls around the hero in random directions, never entirely closing off, via a cellular automaton that looks for walls with a 3x2 area of walkable spaces in front of them, with the space directly in front a regular floor space - the effect of this given enough iterations turns the terrain around you into a maze.
• Generic damage over time, not severe but enough to provide a headwind. Or partial or total disabling of natural regeneration.
• Asmodeus: Some damaging cold effect that happens periodically, or your cold resistance is nullified and replaced with a vulnerability to cold effects.
• Baalzebub: Something to do with insects, either periodic summon insects from nowhere or stronger/more frequent insects
• Juiblex: You may randomly become ill, or have your regeneration dampened or something
• Geryon: Hordes of buffed q generate and rampage periodically.

Turn the Rogue level into its own branch, all levels of the branch operating under the same rules as the Rogue level. At the end of the branch is one of the defunct NetHack bosses such as the Goblin King.

Add multiple sub-branches of Gehennom, each containing a single demon lord’s lair. Killing them is optional, but each one that remains unkilled provides passive effects to thwart the player within Gehennom, especially on the ascension run. The mysterious force could be one such effect. The idea is that it’s not feasible to skip them all in a normal game because the combined effects are too difficult to overcome, but not necessary to kill them all either. You are able to choose which effects you want to put up with.

New side branch, which is extremely difficult. At the end of the branch is an artifact crown, which causes you to become crowned when you wear it. Since crowning titles are bestowed by your god, it is unclear whether this should force the god to crown you and thus break atheist, or merely confer all the effects of being crowned without actually granting you the title.

A new branch with infinite levels, whose level difficulty continues steadily increasing the deeper you go. Monsters killed do not drop anything, except that there is a very small chance, increasing with greater difficulty, of dropping a single wand of wishing. Unlike the rest of the dungeon, monster generation cares only about the level difficulty, ignoring the player’s experience level.

Levels in this branch are non-persistent. To prevent destroying any unique items, you either can’t bring them into the branch at all, or you are prevented from leaving a level in any way while they are on the level somewhere other than your person. Not determined what drinking a cursed potion of gain level would do.

One way to increase the challenge and prevent the hero from resting on the downstairs every level and starting each new level fresh is to suppress or remove natural HP regeneration in this branch.

Using an upstairs will take you back to the branch entrance, which may then close off forever. Possibly, 9/10 of upstairs will just crumble to nothing upon arrival in the level (whether this 9/10 is random or happens regularly every 10 levels isn’t determined). This makes it less easy to decide to bail out, though levelport or branchport would probably still work as escape items.

Not determined is to what degree the branch should enforce the player to spend time on each level. The three proposed options are:

1. No enforcement. The player can go as deep as they want by digging a hole right away with the increased risk it entails.
2. Enforced finding the downstairs. The floor is nondiggable, so the player has to at least reach the downstairs in order to travel further.
3. Enforced battling a certain amount (or all) of the monsters. The downstairs will not let you travel down them unless you have killed a certain amount of monsters on the level.

Make Fort Ludios a multi-leveled branch leading upwards; the upper floors are smaller levels with the same footprint as the base of the building on the bottom level.

Dungeon branches that are completely submerged: their levels have a special level flag that treats you as underwater no matter what the terrain is. Would work better if a breath timer were implemented rather than instant drowning if a magical breathing source is lost. Trying to go down the stairs leading into the branch without the ability to survive underwater is equivalent to jumping into a pool: you will get wet and then crawl out (still on the stairs), without changing levels.

Make the Castle a side branch, putting two down staircases on Medusa, one of which goes to the Valley and the other of which goes to the Castle branch, first preceded by several maze levels.

Subspace branch, which has many entrances and exits to various parts of the dungeon for quick traversal. However, it’s populated with nasty monsters.

Special level or branch that is populated by dinosaurs and an intelligent reptilian humanoid called sleestaks. There is an artifact somewhere in here that is guarded by the dinosaurs and sleestaks.

Restructure Gehennom as follows: the main trunk consists of the Valley, then 5-7 filler cavern/lava levels interspersed with two bribable demon lairs, then the Vibrating Square level (also cavern/lava), then the Sanctum. The Vibrating Square level contains six revealed portals, one of which leads to the Wizard’s Tower, one of which leads to Vlad’s Tower, and the others all lead to demon lairs in which you can’t leave the level until the demon is defeated.

Single-level branches whose portals, found in vaults, disappear after one use; they are subdivisions of the Magic Memory Vault, and modeled after ADOM “vaults”. These are basically challenge levels, smaller and less rewarding than Fort Ludios (the master branch), that contain some nice loot and harder-than-usual monsters. Portals to them can also be found in vaults in Gehennom.