Magic bookshelf dungeon feature, which is heavily inspired by and is functionally similar to the TNNT swap chest, but only involves spellbooks instead of all items (and is not itself an object).

Looting while standing on it gives you a feeling you should put a book on the empty shelf, and if you do, you magically find other books on the shelf. You can see the identities of these books but do not permanently learn them if you didn’t previously know them. Once you take a book from the shelf, it vanishes.

Left up to the implementor whether the books would actually come from other players like the TNNT swap chest does (in which case it might end up filled with low-value or common books; if so, there are various ways this could be mitigated such as the shelf not accepting a book type it already has, or adding in randomly generated books) or whether the books would just be a pool of random ones selected at the start of the game.

An additional possible detail is that you can only see books on the shelf of equal or lower level than the total level of books you yourself have put in. So if you put in a level 1 book, you will only see other level 1 books, but if you then add a level 3 book, you will see books of up to level 4. Or, you always see all books, but only books below this threshold show you the spell and others appear as “a spellbook”. identities

The “Construction Patch”:

• When digging out stone (not necessarily walls) with a pick, rocks may fall on your head with a lowish chance, about 10% per dug square. These deal the least damage if you are wearing a dwarven helm, and a little less than normal if you are wearing some other hard helm. Dwarvish characters have a high chance of dodging the falling debris entirely. Possibly also allow a boulder falling on your head from digging similar to when monsters tunnel.
• You can apply rocks at an adjacent floor square to build a wall. It takes 50 rocks, or 25 if there is a boulder in that square. (If the space is marked as being wall-nondiggable, this either doesn’t work, or flips the space to being diggable.) It takes 1 turn per rock to build it. In the process it creates an immovable object or dungeon feature called “partially-built wall” on that space, which tracks how many rocks are part of it. If you move onto the space, you can dismantle the wall and retrieve the rocks.
• You can apply rocks at an adjacent pool or moat to attempt to fill it. The more rocks, the higher the chance of filling it. This takes only 1 turn.
• Stone to fleshing diggable wall turns it into huge chunks of meat.
• Force bolts from striking wands or the spell scatter rocks off diggable walls they hit, and in roughly 5 shots the wall is destroyed.
• Digging a pit or hole puts a pile of rocks on a random adjacent square.
• When you dig a hole and fall down to the next level, you are usually accompanied by a shower of rocks falling on and around you. Dwarves are more adept at dodging and getting hit by fewer rocks.
• When using a pick to dig a square of natural stone where the four orthogonally adjacent squares are all dug out already, you are asked if you want to carve out a boulder. If you say yes, a boulder is deposited on the new space.

Note that the two boulder-creation methods above run the risk of being exploited for abusable quantities of food if you have stone to flesh available, and the stone-to-flesh-walls method explicitly invokes this.

With respect to other proposals about crafting (involving a craftsmen’s guild or even scattered craftsmen), the process of traveling back and forth to and from it might become busywork. So if players could craft things on their own, that might be better.

• Would probably need properly flavored terrain for workstations, like a furnace or smelter, for certain crafts, otherwise flavor is too weird. (But this creates the problem of having to travel back and forth to it again.)
• Fixed, non-simple recipes (e.g. existing scroll crafting is a simple recipe) are a heavy spoiler tax and should be avoided.
• This could be simple for certain types of items, as in requiring some silver or gold and a diamond to craft a diamond ring, but doesn’t explain where any magical effects come from, and also might weirdly tie crafting recipes to randomized appearances which have previously been meaningless.
• Probably requires a few more “base” crafting materials, some source of leather, some source of wood, etc.
  • Corpses could decay into bones, which disappear themselves with a longer timeout, but in the meantime can be used to craft bone stuff.
• One of the craftable items should be saddles, because they’re very hard to find for non-Knight characters who want to ride.
• Tallow candles should be relatively easy to make, because they can be made out of fat from slain animals.

Allow sinks to be catalysts for alchemizing things. (Or possibly add a “cauldron” as a new piece of dungeon furniture, but that’s iffier.)

• You can dip potions into sinks to pour them down the drain, experiencing the vapor effects in a safe way. (Pouring polymorph down the sink of course polymorphs the sink.) This requires vapor effects to be implemented for many of the potions that don’t currently have any.
• If you don’t pour the potion down the drain, you instead mix it with the fluid from the tap, which is usually water but can already be a random potion.
• Possibly, doing alchemy in/on a sink is more efficient. There are many possible forms this could take, such as:
  • Potions not diluting when you mix them.
  • Reduced or zero chance of an alchemic blast.
  • You can get results from mixing potions that you can’t otherwise. (Flavor for this is weak. Is the character heating them somehow with the hot water?)

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.

A dungeon feature that massively improves your spellcasting success rates while you are standing on it.

Sconces (perhaps a \ found on the walls of dark rooms, and in dark Mines levels, that may contain (lit or unlit) candles. You can untrap or loot them to remove the candle. Could also generate with an oil lamp, which would give you a potion of oil or a partially filled oil lamp when looted.

Desks as dungeon furniture: they can store items like a container, and acts like a table if you are on top of it (if levitating you can interact with it and things on it). Sometimes generates a magic marker inside. Writing scrolls or spellbooks at a desk has some bonus: maybe a higher chance of writing unidentified, or a slightly reduced or capped ink cost. Possibly put one or more in the College of Archaeology, and Warden Arianna’s office for Convicts.

A “reset button” for Sokoban, which restores all the original holes and resets all the original boulders, and places the player on the downstairs (or is reachable only from the downstairs). Probably not activatable after the level is solved. Flavored as some sort of mechanism.

“Painting” dungeon feature / furniture. Players can look at them to see what it’s a painting of, possibly identifying item types they didn’t already know about. Could be free-standing (\) or could be part of the struct rm flags of a wall (|, interactable by farlooking them while adjacent). Might be able to be haunted - can produce a ghost?

Ovens, a dungeon feature (\) that you can use to cook food, light items on fire, and test potions in a safe, controlled manner like you can with rings and sinks. This happens by putting the potion in the oven and it produces some cosmetic message that can be used to identify it.