The first delicatessen generated in the game will always stock food aligned with whatever food-related conducts you have kept up until that point, except for foodless, in which case it stocks only decadent food to tempt you into breaking it.
In the options menu, the player can select something which forces a reload of all non-birth options from the config file, in order to refresh annoying options which are saved with the game and do not pick up on when someone fixes them in their config file.
A potion of growth (or “embiggening”), which lets you temporarily lift boulders, and a potion of shrinkage, which lets you get through narrow diagonal gaps if you would normally be unable to.
Gifts from your god (including gifts not from sacrifice, such as spellbooks) should have their blessedness identified, since your god is very explicitly blessing them.
Physical explosions (those from a gas spore) should blow away doors that are in the blast radius.
You can clean slippery fingers by rubbing a scroll on them, but this makes the scroll useless and destroys it.
You should be able to use a forge to melt down gold items and turn them into gold pieces.
Bones of tortle players contain a tortle shell, which is useless except as an indicator the dead player was a tortle, or as polyfodder.
Magically identifying an iron safe (if you manage to pick one up, that is) allows you to open it, because you identify the combination.
Amulet versus magic, which gives magic resistance when worn but also makes it difficult for the wearer to use magic, translating to a sharp penalty in spellcasting rates and, depending on the implementation, reducing or nullifying the effects of magic items.
Rather than placing random amounts of gold on each tile in a special room that generates gold on each tile (zoo, leprechaun hall, and any other that might get added), bias it so that there is more gold in the corners and along the walls, on the basis that things tend to accumulate in the corners of rooms. Should work on irregularly shaped rooms as well as rectangular ones.
One possible algorithm is that corners get 3 “helpings” of gold placed on them, walls 2, and every other space 1.
Another take is to instead put more gold into the center of the room and less further out, possibly guaranteeing some dragons on top of the biggest piles.
Carrying a substantial number of cursed items in your inventory has some denigrating effect on you. One suggestion is that enough cursed items counts as a negative luckitem similar to a cursed luckstone.
The quest leader either sometimes or always asks for the quest artifact back when you return with it, to replace the weird flavor in most quests that the leader is desperate to get the artifact back but is then completely fine with you adventuring off with it after retrieving it.
If you refuse to give them the artifact back, they turn hostile. If it’s a chance-based system, the chance might be dependent on your alignment record, so a character that has misbehaved is less likely to be found worthy of keeping the artifact. However, since you must have +20 alignment to enter the quest and get a massive amount of alignment from killing the nemesis, it’s questionable whether anyone’s alignment will ever be in a bad enough state to increase the chances. Luck has also been suggested as a variable that influences the chance, but most players will already have maxed their luck by the end of the quest.
In order to keep the player from just dodging the quest leader on their way out of the quest so that they can keep the artifact, various enforcement mechanisms have been proposed:
If you eat a corpse of a monster that drank a potion just before dying, you have a chance of getting some effect from the potion too.
Using a weapon made of glass to force a lock should always end up with the weapon breaking.
When faced with a pickup_burden prompt (“You have a little trouble lifting/removing a foo. Continue?”) deliberately ignore space, forcing the user to enter y, n or q. These prompts commonly come when removing a lot of items from a bag or picking up many items, and the player is spacing through all of them.
A cursed amulet of life saving, if saving you from HP-loss death, will restore a completely random amount of hit points.
Dropping a loadstone has a chance of producing the message “You drop the loadstone right on your foot!” and wounding your legs.
All food generated in Gehennom (including both food generated with the level and after creation time, and corpses) is rotten.
You can chat to the Minetown Watch to pacify them if they’re angry, but it requires high Charisma and Luck to pull off (and is never guaranteed). There probably also needs to be some limiting factor so that you can’t retry this.
Dart and arrow traps should shoot a consistent type of dart or arrow (i.e. not shooting a +1 dart and then a +0 silver dart), and if there is a stack of them pregenerated on the trap those should be consistent with it too.
Hobbit players should always start the game with a non-harmful ring.
If you attempt to push a boulder onto a space where a pet is, it will automatically move out of the way if there is an available space to move to. If not, it stays there and the boulder can’t be pushed. This may or may not cost the pet a move.
Lizard corpses should go tainted like any other corpse, though they will still never rot away completely.
Enchanter, a monster that enchants your gear when it hits you or when you hit it with a weapon, the opposite of a disenchanter. (Not to be confused with the enchanter rank title.)
If a boulder rolls over certain types of comestible, it becomes a pancake. (Which types of comestible isn’t specified; probably it should not be possible to turn corpses, tins, or lower-nutrition-than-pancake permafood into pancakes.)
Magpies, a bird that has a stealing attack; unlike monkeys, the stealing attack is limited to shiny objects (possibly based on their material) that are under a certain weight. Under that rule, rings, gems, and amulets are common targets of theirs. They probably have a rather fast speed, too. They should likely generate in small groups.
Magpies would have an alignment of 0 and lack the M2_HOSTILE flag, and thus may be peaceful to neutrals, but angering one makes all other magpies angry as well.
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.
Improvements to secret doors:
