If you have polymorph control, you can control what any item dipped into a potion of polymorph will become, respecting existing polymorph restrictions (i.e. not controlling the number of charges something will get, and incrementing the recharge count). This allows it to act basically like limited wishing, but it may be okay given the rarity of polymorph potions.
Make more artifacts creatable by naming, with reasonable restrictions based on your role, experience level, alignment, and preexisting enchantment of the weapon, if it is a weapon.
Example: A lawful Priest who is XL 20 can create Demonbane by naming it, provided the mace being named is +5. The enchantment turns to +0 as the magic flows into its new anti-demon powers.
If you give your pet a scroll, and it is a scroll that monsters can normally read, it reads it on its next turn.
In-game achievements, especially role unlocks, should produce a clear message to the player.
New “pauper” conduct, in which you are not allowed to gain any gold pieces in your inventory (gold items like the gold ring and Candelabrum are fine, because they aren’t money).
An interesting side effect is that you can’t sell things in a shop since the shopkeeper will give you money directly for them, unless you manage to somehow remove all the shopkeeper’s gold, enabling you to sell and buy things for store credit.
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.
An option to have your starting pet assigned a random name. The name pool would probably come from a hardcoded list (or even a text file like engrave.txt).
Prevent giants from accidentally moving on top of a boulder in Sokoban, which incurs a luck penalty. This is probably most easily done by only allowing them to move on top of an unpushable boulder by prefixing the move with m.
Another possibility is just to prevent giants from stepping onto boulders in Sokoban at all, giving a message “The ceiling is too low for you to step over this boulder.”
You can wish for specific text on a wished-for T-shirt by specifying “t-shirt which says xxxxx”.
For all “matched pairs” of scrolls and spellbooks (remove curse, fire and fireball, identify, etc), identifying the scroll automatically identifies the spellbook. Possibly vice versa instead, where learning the spellbook automatically identifies the scroll, or both.
Merge the potions of booze and confusion together, because booze is basically just a weaker form of confusion that also has a minimal amount of nutrition. It’s not certain which way they should be merged: deleting booze and favoring confusion has the advantage that monsters can still flavorfully throw it at you in order to cause confusion (you don’t get instantly drunk from being splashed with booze), but deleting confusion and favoring booze is attractive because it’s a more flavorful item in general, what with having a dual confusion/nutrition effect, being nonmagical, contributing to levels like the Wine Cellar, etc.
Tame dragons never drop scales.
Shopkeepers can summon a minion or clone to guard any second door into their shop if one should happen to exist.
Invoking the Amulet of Yendor gives you a random possibly helpful, possibly harmful effect:
Casting wizard lock at Expert skill will transform a door into an iron door or create an iron door.
Setting fire to a web should burn through it, spreading to any adjacent webs and destroying all of them.
Dipping a ring of polymorph control into a potion of polymorph allows you to control the ring it turns into (not its enchantment though, if the ring is enchantable).
Guarantee a random sack somewhere in all Minetown variants.
Scroll of knowledge: rare scroll that directly increases Intelligence when read.
Healers start with higher Intelligence (perhaps at the cost of their high starting Charisma, which they don’t need as much). Priests could stand to have guaranteed a bit more Int and monks a bit more Wisdom, as well.
Mind flayers have to grapple your head before they can successfully suck your brain (like in D&D), forcing them to spend a turn doing this. If you have a greased helm, this gives you at least one extra turn to act since they will not be able to grapple your head until the grease dissolves.
This would probably best be implemented by giving them a sticky grab or bear hug attack and ignoring the existence of their tentacle attack if they aren’t already grappling you (or you are being held by another enemy and thus can’t avoid them). Either way, checking u.ustuck is the key.
Possibly, they need to spend another attack getting your helm off, which will unequip it, though this will get weird if your helm is cursed. A cursed helm shouldn’t offer total protection against them. Possibly, they should be able to remove a cursed helm (like nymphs and foocubi do) despite its curse; this could be handwaved as them using their psionic powers to do it.
In variants that implement zombies eating your brain, it should work on basically this same system, where the zombie needs to hold onto you before it can eat your brain (and which also works that way in D&D).
Additional temporary effects accompany drinking a potion of booze. The effects wear off when the confusion does (so if you extend it by, say, drinking a potion of confusion, the effects are prolonged). There is consensus that there should be both positive and negative effects; all of the following have been proposed:
Carrying gold items openly causes leprechauns, dragons, and Croesus to be automatically aggravated.
Intelligence can be abused and exercised, but unlike other stats, exercise will never bring it above its base value (or the value you have raised it to through gain ability).
Sources of abuse: mind flayer brain eating, zombie attacks. Sources of exercise: reading spellbooks, writing spellbooks, writing scrolls, learning a new spell, getting a major Oracle consultation for the first time, possibly some of the uncommon, non-farmable ways stolen from the things that exercise Wisdom.
Fire and cold should both work as a cone, and should spread out over distance and possibly hit multiple targets, but with damage decreasing over distance.
Archeologists should start with searching rather than having to get to XL 10 for it. To compensate, they now get stealth at XL 10 instead of 1.
Command (generalization of #tip, or #dump, have both been suggested) to transfer all items from one container into another container without having to temporarily place them in your inventory. It would be better but perhaps harder to implement if you could pick and choose which items were being transferred, rather than all of them.
