Artifact-like system for monsters that applies a new set of stats on top of an existing monster’s stat block. The monster is not G_UNIQUE, but only one of it can spawn in a game.
A simpler solution would be just to add unique monsters to the monster list and figure out a way to allow these monsters to spawn randomly.
Reimagine the Rogue quest plot where the quest artifact is owned by a rich guy and you’re sent on a mission to steal it, sneaking into his estate, bypassing all his security guards and systems, and covertly entering his mansion.
Ideally, it would require cunning and inventiveness like the current quest does, not simply being a quest you can slaughter your way through. It could still use the idea of having the entry point and destination on a level be in disconnected areas of the map separated by non-phaseable walls.
The nemesis can be made weak and trivial to kill if you actually get to him (because he is just a fat old rich guy), with the possible exception of if you get noticed by or kill him, he will call in all his backup to stop you.
For this to work, the quest artifact would probably have to be changed from the Master Key of Thievery to something else that a collector would have. Alternatively, the goal of the quest could just be a macguffin, with the quest leader having the Master Key of Thievery and they exchange it for the macguffin when you return with it.
Cavemen have a lot of experience traversing tight spaces in caves, and thus are always able to squeeze through a diagonal space (except possibly in Sokoban).
Alternatively, they are able to squeeze through diagonal spaces while carrying much more weight than other roles.
A demon lord who occasionally summons demons (or some other sort of minion) and, when killed, will possess the body of one of his minions, so you need to kill all of the summons before he can be finally killed.
Solve the problem of pets wasting their hard-trained apport by picking up and dropping objects randomly all over the dungeon, by triggering them only to use it when the hero plays any instrument (or maybe any non-magical instrument). Bonus points if the player can train the pet by playing an arbitrary sequence of notes (chosen by the player) on tonal instruments.
Artifact tooled horn Horn of the Wild that summons a number of difficulty-appropriate tame animals to fight for you. (They might untame or despawn after a while.)
Artifact ring of searching that protects you completely from triggering a trap you didn’t already know about.
If you eat a lizard’s brain while turning to stone, it cures your stoning.
If you attempt to move into a ghost’s space (either if it’s invisible and unseen by you, or by m-moving, not by moving normally towards it when you know something’s there which would still be an attack), you successfully move there, displace the ghost to an adjacent space, and take some damage from creepily passing through a ghost. If this is implemented in an extra evil way, this could be cold damage that destroys potions.
Wielding a weapon while getting crowned either unrestricts it if you were Restricted in it, or otherwise raises your skill cap an additional level, up to Expert. Though this is obviously bad for inter-role balance.
Add a #pour command, which allows you to pour a potion on your own or an adjacent space. This allows you to do things like pour healing potions on your pet rather than smashing them with it, possibly pouring acid and other harmful potions on adjacent monsters, pouring water on fire elementals and other fiery monsters, etc.
Add a bit to the monst struct that tracks whether the monster is hiding on the ceiling or not. (Only valid for things like wumpuses, piercers, and perhaps bats but not actually since bats don’t roost on the ceiling when inactive.)
Then, when polymorphed into a wumpus or piercer, you can use < when not on stairs to climb onto the ceiling and > to climb back onto the floor, but only when adjacent to a wall.
When you are carrying a candy bar, ants are attracted to you, even if peaceful. Candy bars should also be a treat for pet ants.
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.
If an aklys slips out of your hands because your fingers are slippery, it winds up unwielded in your inventory rather than on the floor, because it’s still attached to you by the strap.
When you use a magic whistle, if you have more than a certain number (3 or so) pets teleporting to your side, condense it into a single message saying “Your pets appear around you.”
Dragonbane starts off as just a weapon with a damage bonus versus dragons, but it gains properties corresponding to every type of adult dragon you have killed with it. So when you kill a red dragon with it, it now gives you fire resistance and/or does fire damage, then you kill a black dragon and it now gives you fire and disintegration resistance and/or does fire and disintegration damage, and so on.
This doesn’t have to be Dragonbane, the concept of an artifact that powers up by killing different monsters could apply to something else, but Dragonbane is a good example since dragons have a big diversity of obvious properties and resistances.
To keep it from becoming overpowered, it could stack up to 2 or 3 properties from the last 2 or 3 unique types of dragons killed so long as neither property is something powerful like reflection or magic resistance (which would clear all other properties).
Some method of allowing the player to find out what the unselected two Sokoban prizes were, after picking up the chosen prize and the other two poof out of existence.
Gold bugs have some interaction with graves if there is one on the level. Perhaps they are found hiding near graves, or will try to pathfind to a grave and dig it up.
Track the highest-reached enchantment of enchantable weapons and armor. If it gets cancelled or disenchanted below this peak amount, you can dip it in a potion of restore ability to immediately raise it back to that peak.
Add a #notes command, which opens up a blank text editor window where you can type anything you want. The notes are saved along with the game and can be referenced anytime from within it.
To prevent this being a hugely complicated undertaking (basically implementing a text editor in the game, which won’t mesh particularly well with players used to other text editors), one suggestion is to use the shell’s default editor, but then this becomes akin to just using out-of-game notes anyway.
Another suggestion is to implement it using a system similar to autopickup exceptions: the player can add, edit, list, and delete one-line notes, which doesn’t require implementing any text editing capability the game doesn’t already have.
After killing certain type(s) of monsters (such as the monarch of a throne room), a timer may start that spawns an avenging posse of related monsters nearby.
Rather than having dragonhide items be generically “dragonhide”, let them each be a certain dragon color, which cannot be specified by wishing. This item does not confer the same extrinsic it would if it were body armor. Instead, when you are wearing dragon scales or mail and a dragonhide item of the same color in another slot, you gain a very powerful extrinsic which cannot be gained otherwise. E.g. cancellation immunity for gray dragon armor.
The idea is to discourage everyone continuing to wear gray or silver dragon scale mail: if you find or wish for dragonhide gear and get some other color, it may be attractive to wear dragon scale mail of that color instead in order to get the powerful extrinsic.
In variants with some form of a randomly generated garden room - whether a special room, themed room, or random vault - gnome statues generate in them.
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).
When a wand of cancellation is placed into a bag of holding, rather than blowing it up, it instead uses up (all of?) the wand’s charges and turns the bag into a sack.
For consistency, bags of holding should probably turn into sacks when zapped with cancellation as well.
This forces potentially interesting choices on cursed bags of holding in bones files, since now cancellation cannot safely be used to loot all the contents and get the bag too.
Rather than giving each demon lord a fixed weapon with a fixed set of artifact effects or object property, create a set of powerful weapons that each demon lord randomly gets one from when they generate.
This might not apply if a demon lord has a strong lore reason for a specific weapon, such as Yeenoghu wielding a flail.
A spell that grants temporary magical breathing. This could be used in lieu of the magical breathing amulet to go underwater for short durations, but would also be very useful in variants that have suffocating engulfers.
There should be a spell (probably on the player’s side, possibly on the monster’s side) that dispels magical buffs such as protection and reflection. Or else, if adding a new spell is unwanted, this effect could be folded into cancellation instead.
A silence spell for either players or monsters or both. Not specified whether it would be area-of-effect or targeted at specific creatures. The main function of silence effects would be to prevent spellcasting. Not specified whether this would also affect reading scrolls (though probably not since you can “cogitate” the formula on scrolls if polymorphed into a speechless form).
However, this may require defining certain existing spells as not requiring speech, because it does not seem entirely fair to take away all of someone’s escape or healing spells with fairly low level magic.
When you read a scroll of fire inside an engulfing monster, the fire explosion hits it 8 or 9 times instead of just once.
Remove Stormbringer’s automatic attacking of peaceful monsters and instead incentivize attacking peaceful monsters by giving the hero some benefit, such as lowering prayer timeout, whenever attacking a peaceful monster with it.
In variants where your god can gift non-artifacts, they should sometimes gift you a stack of projectiles (ideally they can match it to some ranged weapon you have if they are feeling nice). It would be useful even when the player already has a favored melee weapon.
You can apply an equipped small shield (or possibly other types of shields) to attack a monster with a shield bash. This could be treated either like a blunt weapon attack, or more likely as a special effect which has a chance of stunning the target. Stunning odds could be higher for either more martial-based roles, or could use a shield skill and scale with that.
There should be some special effect, even just an acknowledging message, when trying to apply a mirror to a cockatrice, since the encyclopedia mentions its own reflection is fatal to it and the materials to make it look at its reflection exist in the game.
When priests attempt to throw edged weapons at something, the weapons/ammo often slips in the wrong direction as if they were cursed (even if they aren’t actually). Blunt weapons such as sling ammo or throwing Mjollnir might not have this restriction.
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.
Rarely, a player monster will be generated as following a random conduct or conducts. This influences both their gear (e.g. a nudist player monster will not have armor, a zen player monster will wear a blindfold) as well as their behavior (a pacifist player monster will not attack).
Hellfire from monster casting, being inspired by Ghost Rider, should in addition to ignoring fire resistance slow the player down, since it does spiritual damage that reduces the victim’s will to act.
Unicorns are more likely to generate peaceful if you are celibate and have not yet dallied with a foocubus in your game. (Since coaligned unicorns are peaceful anyway, this would affect cross-aligned ones only.)
If a digesting engulfer eats an e monster that explodes (either actively or upon death) or potentially any monster with an explosion attack, the monster is assumed to explode inside the engulfer, who takes double damage from that attack (or 8 times damage, if the explosion is considered to have hit them 8 times) and is stunned and immobilized for a few turns, unless they resisted the explosion’s damage type in which case they only suffer that for 1 turn.
This should also extend to other explosions inside engulfers (most of these would be player-created: e.g. reading a scroll of fire or breaking a wand while engulfed).
Make the Gnomish Sewers Mines’ End in EvilHack less aggravating for the player who lacks teleport control: instead of having to jump into teleport traps and teleport around the level randomly until winding up in the hidden luckstone room, make one specific teleport trap always direct to that room.
Water walking boots do not sink in water. They stay on top of the surface and can be picked up by something else that has water walking.
You should be able to kick downwards, presuming you can reach the floor, to deliberately scuff an engraving beneath you. This will be most useful on semi-permanent engravings since a dust engraving can just be wiped out easily and a burnt engraving won’t scuff.
Force-fighting a monsterless pool of water or moat or perhaps even lava while wielding Frost Brand should freeze that square into ice (or ground if it was lava).
Wishes that don’t directly match anything get passed through a Levenshtein distance algorithm to find the nearest thing to which it matches. Then ideally the game would ask “Nothing fitting that description exists; did you mean to enter [foo]?” and answering yes will wish for that instead.
Artifact bow that acts like an infinity bow in Minecraft: if you have bow-compatible ammo in your quiver, it shoots a phantom copy of that ammo (never multishotting) without using up the real ammo. When this phantom missile hits the floor, it disappears.
A damage type that shuffles around the player’s intrinsics, never taking any away for a net loss, but always rearranging them, so you could lose fire resistance but gain teleport control, or lose telepathy in exchange for intrinsic protection from shape changers.
A tree hit by a fire ray or explosion should instantly incinerate, provided it’s not marked non-diggable (petrified). Likewise, a tree hit by a disintegration blast should disintegrate.
Anthill: a dungeon feature found exclusively in antholes that acts as a monster spawner for ants. The ants produced will all be the same type as the anthole is, and ants will not spawn out of it when there are already a certain number of ants in the area. Eventually it stops spawning ants (perhaps with a system where it rolls every time it creates a new ant and if it fails the roll it increments an internal counter; the higher the counter gets the lower the chance of spawning more ants), or the player can prematurely destroy it by digging it.
To compensate for the extra ants spawned, antholes could no longer be packed full of ants.
Eating the corpses of mummies may cure terminal illness (though they may also still give terminal illness, being old corpses), because powdered mummy has been used as a healing agent.
Hitting a shambling horror with polymorph should not polymorph it into something else; instead it should rerandomize its stats and attacks.
This would be better if shambling horrors were randomized per monster rather than per species; it doesn’t make much sense to polymorph a horror on dungeon level 20 and a preexisting horror on dungeon level 17, or new horrors that haven’t even generated yet, get rerandomized.
When a corpse (possibly only a fleshy, blood-bearing corpse?) falls into water, any nearby sharks and/or piranhas become “frenzied”, gaining bonuses, for some time. Possibly they could also try to converge on the space containing the corpse and maybe eat it.
Water nymphs may create a pool on their spot when killed. Items they stole from the player fall into it, of course.
Wood nymphs may create a tree on their spot when killed, and mountain nymphs may leave a boulder.
You can convince peaceful intelligent monsters to join your cause (taming them) by chatting with them. The outcome depends on several factors: your respective alignments (lawfuls have a very hard time recruiting chaotic monsters), respective levels, respective races, your Charisma (which should be a large factor), and possibly others. Failing might turn the monster hostile, or do nothing. You only get one attempt per monster; if they don’t want to join you, trying again will never work. More complex behavior could possibly be implemented with the monster demanding something from you or making you do something before they will follow you. E.g. “I’ll only join you for 100 zorkmids,” or “Bring me the helms of three goblins to prove your worth!”
Internally, this would probably work by having a new flag “recruitable” on a monster, which is only set to true when a monster generates as peaceful (and is not set at all for certain monster types like shopkeepers and priests). Chatting first checks this flag: a taming attempt is only made if it is true, and it is set to false regardless of the taming outcome. Some peaceful monsters of a recruitable species could also generate with the recruitable flag as false.
To avoid this conflicting with existing #chat, there are a few options:
