Shorten Gehennom drastically, paring it down to a few mandatory levels (the Valley, the Wizard’s Tower (containing Vlad’s Tower entrance), the vibrating square level containing the fake Wizard’s Tower to portal into the real one) with no demon lord lairs and no filler. In exchange, once you start escaping the Sanctum with the Amulet, any level you reenter for the first time gets partly overwritten with Gehennom elements – rivers of lava, twisted mazes, and in particular, the demon lords. However, enough areas of the map will be left in their original states so that it remains recognizable. In particular this is aimed at making sure any stash you have made may not survive the process.

There are several motivations for this:

• Reduce the common feeling of “the game is over after the Castle” by putting only a few things between the Castle and the ascension run.
• Put the main challenge of Gehennom on the way out of the dungeon, not on the way in.
• Make it uncertain that the player will be able to go back to a big stash of items after grabbing the Amulet and take whatever they need before entering the Planes.
• Reduce the number of situations where the player can simply levelport away from a hairy problem such as a tough demon lord, collect the appropriate gear to fight them, and return (dipping into and out of Gehennom).
• Remove a Gehennom-worth of items the player finds on the ground and in monster inventories (where “the difficulty is flat but the loot keeps coming”).
• Mitigate the tedium of knowing you’re as powerful as you’re ever going to get but still have to retrace 50 explored levels. Relatedly, remove the incentive – the ability, even – to go tunneling through mazes.

Some of the non-guaranteed demon lords (provided they aren’t prematurely summoned into the game) show up randomly in Gehennom on the ascension run.

New monster “Phantom of War”, a powerful player monster style @ that appears on either the Astral Plane or elsewhere on the ascension run, but only if the player has successfully maintained pacifist conduct up until that point.

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.

If you escape the Black Market by branchporting, One-eyed Sam will pursue you on the ascension run.

When the demon lords all levelport away into Gehennom on the ascension run, they always land on the downstairs rather than being randomly placed, because they’re smart enough to lie in ambush for you.

Extension of the feature in several variants where monster spawns are concentrated on the upstairs during the ascension run: occasionally, instead of spawning a monster, generate an organized group which is trying to get the Amulet, usually made up of sapient monsters (such as a group of soldiers, or a few priests of the same god, or some elves led by a couple elf-lords). Possibly, this only happens after you get back out of Gehennom and are again visible to the other gods.

Assuming an implementation in which Gehennom starts to get destroyed after you remove the Amulet: When you kill the high priest of Moloch, he gives you a multiline death message calling you a fool and saying you don’t know what you have done, and maybe hinting a little bit at why Hell is about to go to hell.

If the demigod flag is set, increase the speed of all non-sessile monsters (by giving them extra movement points).

The Arch Priest specifically offers to open up a magic portal to the Plane of Earth if you talk to him with the Amulet of Yendor, as a Priest benefit, to skip the last dozen or so levels of the Dungeons of Doom.

Asmodeus and Baalzebub have a chance of re-appearing hostile to their levels (not a certainty; if they always came back there’d be no reason not to kill them off) when the player is on the way back up with the Amulet. Flavor-wise, this is because the player only paid for safe passage ‘‘down’’, and now the player has their coveted Amulet.

You can only use cursed potions of gain level once or twice while carrying the Amulet. After a few uses, the Amulet will start to pull you back down as you rise up, wasting the potion.

While you are on the ascension run, mimics prefer to disguise themselves as upstairs. It also edits your memories to make you think you remember the stair being where the mimic was (in order to fool the travel command routing to the correct upstairs anyway).

Replace the mysterious force with “dark energy”, which starts pooling from the high altar of Moloch soon after you get the Amulet, and thereafter from the downstairs of a given level. If you are caught by the dark energy, you start taking a bunch of damage, limiting the amount of time you can spend on levels after getting the Amulet.

Closed-for-inventory shops, if you encounter them again on the ascension run, will now be open.

The ascension run through the Dungeons of Doom (the instant you come back into your god’s sphere of influence) is trivially easy: your god will regularly smite any enemy that dares attack you, and will ignore prayer timeout when answering prayer (but only to fix problems; if timeout is not 0, the god will not grant you any boons.) However, once you reach the Planes, the other gods step in and start interfering with the god so that they can’t directly help you anymore. These other gods don’t want to kill you since you’re still bringing the Amulet closer to them. But when you reach Astral, the other gods will do all they can to kill you, relieve you of the Amulet, and bring it to their own high altar. Your god sends you several A (might be Aleaxes, ki-rins or possibly even Archons) instead of just one, but you are now faced with elite teams of player monsters, priests, and A sent by the other gods, who have amulet-stealing attacks. The gods’ struggle to each get the Amulet manifests in all sorts of ways: disintegration beams blasting at you but being redirected onto a hapless monster nearby, inventory cursing, lightning bolts, resurrecting the corpses of dead player monsters or priests, and so on.

The demon lords take no interest in you until you are on the ascension run with the Amulet. At which point they attack.

Gods’ “Prove thyself worthy or perish” message is flavored as “Prove thyself worthy, because I can do no more for you”. On the Planes, the gods’ balance of power prevents your deity from granting you any extra help (apart from sending angels when you arrive in Astral). If this were not the case, one would expect to be able to breeze through the Planes, with your god smiting down any enemy that might threaten you getting them their Amulet. Prayer will not work, though it will still break atheist conduct.

Give the player a slightly different warning if they attempt to go up on the DL1 upstairs after handling the Amulet, if they do not have the real one.