Convert the sleeping gas trap to just “gas trap”, and make it scale based on the difficulty. Each individual trap releases a single type of gas; which type is partially dependent on the level difficulty. At low levels, they all emit sleeping gas like normal. At higher levels, they emit stunning hallucination gas like container traps, clouds of poison gas, and maybe even nastier gases that reduce speed or miasmas that cause illness.

When hallucinating, randomize dragons’ colors and glyphs among all dragon colors/glyphs, and allow messages about them to use hallucinatory colors, e.g. “The mottled dragon bites!”

Drinking an identified potion of hallucination or eating a corpse or tin of a hallucinogenic monster as a Knight carries an alignment penalty.

Additional YAFMs that may replace the “You hear your heart beat” message for applying a cursed stethoscope at yourself:

• If hallucinating, “You hear a soothsayer with the weather forecast.” This is followed by either “Gehennom will get a rain of burning pitch later today.” or “The dungeon will be cool, with a stony gray overcast.”
• Otherwise, if undead, “You hear the ocean’s roar.”
• Otherwise, if a Wizard, “You hear yourself mumbling curses.”
• Otherwise, the usual heartbeat message.

Hallucinatory alternative to the typical you’re-about-to-die messages: “You hear the fat lady warming up.”

Remove the ability of unicorn horns to cure hallucination, as otherwise it’s a trivial status effect to fix once you have one.

While hallucinating, the entire map (or at least the parts you can see) should be rendered in rainbow colors. If your terminal supports 256-bit color, it uses a very fine-grained rainbow rather than the simple 16 colors.

YAFM when you are hallucinating and would hear one of the “sink on the level” noises: “You have a sinking feeling”, or “You hear something that gives you a sinking feeling”.

In the context of restoring the tension and strategizing created by encountering a mind flayer, which used to be a lot higher when their amnesia caused forgetting maps and discoveries:

The psychic blast of a mind flayer may make you hallucinate, to create short-term tension, and possibly create long-term strategic tension by counting as Intelligence abuse.

However, since mind blasts are a lot less avoidable and harder to strategize around than getting into melee with a mind flayer, it may be better to add these as additional things they can do in melee (but probably not Intelligence abuse, since they already directly drain Intelligence points).

Have a special hallucination message if Baalzebub gates something in: “Baalzebub has a devil put aside for you!”

When hallucinating, pass all messages through a thesaurizing routine, replacing most words with an offbeat synonym, before printing them.

When hallucinating and pushing a boulder, the word “boulder” should be replaced in the message with a random object. Possibly this should be extended to any message using xname() to format an object.

Add YAFMs:

• Combat messages produced when you attack a hallucinogen-distorted fog cloud are replaced by “You attack thick air.”
• When you try to engrave when engulfed by a dust vortex: “You try to write in the dust, but it won’t stand still!”
• When you get out of an air elemental (that you didn’t kill) while hallucinating: “I don’t think we’re in Kansas anymore.”
• When you attempt to move into a Mordor orc with the m prefix: “You fail to simply walk into the Mordor orc.”
• When a sasquatch is blinded by a camera flash: “Unfortunately, that picture’s probably going to come out blurry.”

When you hallucinate, you see phantom enemies that aren’t really there. They may or may not appear to move, but don’t actually exist and will disappear if interacted with.

One way to do this could be to make invisible I monster symbols affected by hallucination, and randomly place them around the player when they hallucinate.

An option that changes all the game’s messages to their hallucinatory counterparts, without requiring the player to be hallucinating, and without affecting the symbols displayed on the map. Messages that mention monsters turn them into fake hallucinatory monsters, but farlook will represent them accurately.

While you are hallucinating, any parrot corpses you come across are rendered as “ex-parrot” instead of “parrot corpse”.

Add a new type of eye with a hallucination-inducing active gaze attack. It could be called either “third eye” or “pseyechedelic”.

If you get a black pudding from kicking a sink and you are hallucinating, print a YAFM “How can you have any pudding if you don’t eat your meat?”

Give violet fungi a hallucination-inducing touch attack. This either replaces or adds to their existing weak physical damage attack.

Add hallucinatory artifacts (it’s not clear where these would actually appear in the game): The Lost Orb of Phanastacoria, the Bizarro Orgasmatron.

If you are hallucinating, replace the message “You can’t fight yourself.” with “You can’t come to terms with your inner conflicts.”

For variants that implement terrain recoloring while hallucinating: Don’t select the color randomly. Instead use Perlin noise or other continuous noise so that contiguous regions will have the same colors.

When starting or resuming the game while hallucinating and during full moon, replace “You are lucky! Full moon tonight.” with “You’re on the moon tonight!”

A level or branch that forces permanent hallucination while you’re in it. Hallucination blocking from Grayswandir may or may not function.

Dart traps can make you fall asleep, go blind, hallucinate, get confused, etc. This would mesh well with #1922.

Give a YAFM when you gain very fast speed from any source while hallucinating: “Gotta go fast!”

Applying a looking glass cures blindness, in some very odd uncommon set of circumstances (like when hallucinating).

Allow monsters to hallucinate (mostly from the same sources that cause the player to hallucinate, e.g. exploding black light). Hallucinating monsters will, after choosing a target, refuse to attack it 90% of the time (because it sees it as a fellow hostile monster). They also will not pathfind to items on the floor because they cannot see them clearly.

In the absence of monster hallucination being implemented, make a monster stunned whenever it would become hallucinating.

Hallucinatory message for squeaky boards: “You hear a chicken squawk a B note loudly.”

When hallucinating, replace “You hear a chugging sound” with either “You hear a steam locomotive passing by” or “You hear someone chant ‘Chug, chug, chug!’”

Hallucinatory trap names for when you look at traps while hallucinating: “slime pit”, “jack-in-a-box”, “buzzsaw trap”, “spiked floor”, “axeblade trap”, “queasy board”, “revolving wall”, “uneven floor”, “anti-anti-magic field”, “ice trap”, “finger trap”.

When starting or restoring the game while hallucinating, after the “welcome to NetHack!” message, print the message “NetHack is filmed in front of a live studio audience.”

All instances of “mysterious force” are changed to “normal force” when you’re hallucinating.

When either 1) you are hallucinating and hit something well enough to have gotten a ! on the hit message or 2) hit something with a type weakness (fire versus cold-resistant, cold versus fire-resistant, electricity versus water, etc), an additional “It’s super effective!” message is printed.

When you are both hallucinating and weak from hunger, monsters start appearing as % instead of regular hallucinatory glyphs.

Falling rock traps are reflavored as thwomps from Mario if you are hallucinating.

If you are a Caveman, you get telepathy or clairvoyance while you are hallucinating.

Drinking booze while already under its effects, or occasionally when its confusion effect wears off, causes hallucination.

When hallucinating, you hear monsters that can speak say funny things. Possibly only when chatted to; they say “O great wise [bogusmon], how may I help us defend us all against wicked adventurers who quest for the sacred Amulet?”

Monster hallucination, if implemented as a status, should be rather stronger than confusion: when confused, monsters can still see what the other monsters around them are, but when hallucinating they ought to see the same random monsters as the player does, and lash out at any of them.

Chatting to trolls while hallucinating makes them appear to say internet-troll phrases: “Problem?” “U mad bro?” “Trololol!”

Hallucination should prevent against all death magic, including death rays, using the “near death experience” logic. Not just the touch of death.

Skeletons, or any other monster with MS_BONES, don’t paralyze you by rattling their bones if you’re hallucinating; instead you get a message about it playing the xylophone.

Hallucination should cause statues to be seen as monsters that don’t move and perform nonsense actions.

Add hallucination effects to (many, perhaps all) scrolls:

• Scroll of punishment: changes your Luck based on scroll beatitude

Any gaze attack which is prevented by blindness (one which is visual in nature) is prevented by hallucination, or at least the effects are reduced or mitigated. Possibly archons’ blinding gaze should be exempted from this, with the hallucinatory message being “The power of the Aurora overwhelms you!”