Eating a monster egg (possibly after using some cooking system to prepare it) has a chance of giving you some intrinsics that the monster corpse can ordinarily confer.
A death ray zapped over a monster egg on the floor kills it, making it so that it will never hatch.
Possibly, this effect could also be achieved by erodeproofing or canceling the egg.
The line-editing functionality currently provided by compiling in EDIT_GETLIN should be moved to a boolean option on all platforms it is supported, because about half of all players will not like it whether it is forced on or forced off.
Unicorn horn skill should factor into, or even be the primary factor in, whether using a unicorn horn cures you of an affliction.
Instead of books having spestudied charges which leads to a lot of issues with polypiling, you read them once and they disappear, but you get 3 times the spell memory. This is intended to remove tedious spellbook micromanagement.
Because vomiting only costs 20 nutrition, which is a strangely fixed amount and not very much, make it instead cost a proportion (say half) of your current nutrition, with a minimum of 20 if half of your current nutrition is less than 20.
Armor of life saving (unspecified whether it would be magical body armor or some other sort of armor like a helm, or even an object property on existing armor). When it saves your life, it crumbles to dust like the amulet does, as well as any other source of life saving you happened to have, to prevent double-life-saving exploits.
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).
When you are inside a tended shop, that shopkeeper’s sell prices of items in your open inventory are displayed along with the item names.
Archons block teleportation on any level they’re on like demon lords do, because they’re otherwise too easy to avoid.
Level that contains a structure with a lot of gargoyle statues. Some of the statues are statue traps.
Add gargoyles (or statues of gargoyles) to the Castle.
Outside the Plane of Air (where there is no gravity), stepping onto air terrain automatically makes you fall to your death unless you are levitating or flying. (Or possibly you merely fall to a lower level, taking a fair amount of damage, or you have so far to fall that it takes a couple turns to hit the bottom, in which you have a couple turns to take some action to save yourself, by levitating or flying or whatever). However, you are prompted to confirm stepping out into the open air if it isn’t safe to do so.
Items dropped into open air either end up randomly placed on a lower level if there’s a sensible lower level to place them on, or vanish forever (though in that case an exception needs to be made for the unique items).
If falling into air is an instadeath, life saving acts the same as if you die in lava; it puts you on a safe location (“You find yourself back on solid land again”).
Air can use the W_NONDIGGABLE flag, or possibly one of the other struct rm flag bits, to represent a wind barrier, which the level designer can use to make a region of air impassible. Attempting to move onto such a space produces a message like “A strong gust blows you back!” and makes you lose the turn.
One of the greatest problems with air terrain is what ASCII character to display it as; existing implementations use just regular space (which is what it displays as on the Plane of Air), but this is easily mistaken for stone, which can lead to players unexpectedly falling to their death if there is no safeguard against wandering off a cliff, and would present a problem if there were ever a air/stone boundary, which would be invisible. Other suggestions include: space, but highlighted with the terminal’s black color ( ), black pound sign (#), black tilde (~), black right brace (}), or even just gray counterparts of these. All of these have various downsides; for instance, it must be expected that they will render as dark blue for some players who have use_darkgray turned off.
Remove your experience level as a factor from the logic that determines how large a newly generated monster group will be. Instead, scale the group size based on depth. (And to take this further, groups created by magical means such as create monster should be independent of both factors).
Shining spellbooks give off as much light as a candle when wielded.
Centaurs can use lances as if they were riding.
Add “reach the Valley of the Dead carrying the Amulet” (or the Castle) as an achievement tracked by the game.
Add stunning and confusion spheres, which cause those effects when they explode.
When multiple-turn searching, stop when a new monster enters your field of vision.
Instead of being perpetually rechargeable (that opens up a lot of exploits and farming like smoky potion farming and infinite altar farming with the Platinum Yendorian Express Card), horns of plenty now stop being rechargeable after 7 recharges.
The treasure found under randomly generated gravestones should be more treasure-like or the sort of items that get buried in graves in real life, rather than just random objects.
The game opening text for certain roles is changed from “It is written in the Book of [deity]:”
Yellow dragon scale mail gives petrification resistance instead of (or possibly in addition to) acid resistance.
When you get arrested by the Watch or a guard, you are teleported to a prison level, from which you must escape.
Certain monsters (e.g. the Riders) shouldn’t be able to be frightened by getting a ghost from a bottle.
Rogues can build and set traps, more types of traps than just plain pits and land mines and bear traps. Traps may consume some types of items to be set, like a sleeping gas trap will consume potions of sleeping. This should probably not be totally reversible through untrapping. Intended so the player can pick their battles and set up traps in an advantageous position.
You can trigger land mines from a safe distance by hitting the square with a polearm.
Rebalance armor so that all “mail” armor and most of the iron body armor in general is not useless. Ideally, the worst iron armor (orcish chain mail) should be considerably better than studded leather, but they are equivalent. The ideal balance, keeping leather armors and all weights constant and not accounting for to-hit or damage reduction, is probably something like the mails going up to 9 or 10 AC, and splint and plate getting up to around 14, but this is not possible to implement without changing the combat system.
Make the Magic Mirror of Merlin give slotless reflection instead of magic resistance; this is more thematic and makes for more interesting strategy.
Remove instances of “bad RNG” contributing to forms of instadeath or a disproportionate bad effect for a RNG decision made mostly or completely independently of the player’s decisions, because they just add randomness or variance to the outcome of the game:
MSGTYPE:replace to replace a specified message with another one.
