Ideas for a Sudoku puzzle system that could coexist with or replace Sokoban:

• The puzzle part of the level would be represented by an 11x11 grid (9 3x3 areas with 2 rows/columns of some other terrain to separate them).
• The solution must be given by engraving numbers on squares, with certain numbers burnt into the floor. This would require a level flag that provides 2 special cases to engravings: 1) that non-Elbereth engravings do not degrade normally, so you can write numbers in the dust without smudging them; and 2) it is impossible to erase a burnt engraving.
• The solution must be given by dropping rocks of the appropriate quantity onto the squares of the grid to represent each number.
• Both of the above solutions have the issue that the grid is practically unreadable and it basically forces the player to copy the puzzle out of the game, solve it, then copy the solution back in. One solution is to have spaces containing nothing except the requisite solution display as one of a set of 9 new glyphs that display as the number 1-9.
• Another solution is to avoid numbers and use object classes (weapon, armor, scroll, ring, wand, potion, gem, spellbook, and amulet), since there is no particular reason Sudoku has to use the numbers 1-9.
  • This means the puzzle would be solved by having 1 of each object class in each row, column, and sub-grid.
  • The “fixed” objects provided as a starting point could either be immovable, or movable but required to put back in place for the puzzle to be solved (i.e. the puzzle is checking not for any valid Sudoku solution, but a valid Sudoku solution in which the starting objects haven’t moved).
  • The main issue with this suggestion is avoiding providing the player with a bunch of free resources and not requiring them to amass 7-9 of each object class before starting. One way to work around it is to add a new object to each object class that does nothing and never generates outside of the Sudoku level, where exactly 9 of each will appear in every puzzle between the initial ones and the “stock piles”.

When running or traveling using the travel command, the hero should not stop to read any engravings or gravestones they happen to pass over.

Certain deaths (i.e. most HP deaths, but not things like disintegration or sliming) should let you scrawl a bit of player-chosen text in the dirt with your finger which persists in the bones file. This engraving is of blood if your current form has blood, and dust otherwise.

This is slightly technically complicated because the bones file gravestone also stores an engraving and there cannot be two engravings on one space; one solution is to engrave the message on an adjacent square.

In regular dungeon levels, a certain engraving can occasionally generate which has treasure buried beneath it.

(Note: This idea predates the 3.7 themed room containing buried treasure and an engraving elsewhere on the level which points to it.)

Grimtooth can be used to engrave a special name, similar to Elbereth, that scares only elves and hobbits.

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.

A monster, possibly called a “maid”, that cleans up the dungeon. It will pick items lying around on the floor, move chests and boxes into corners, wipe out engravings it finds on the floor, and so forth.

Engraving with a wand of create monster on top of a single-letter engraving has a chance of creating a monster of that letter class. (If it fails to do this, it will create random monsters as normal for the wand.)

Possibly, the chance of it succeeding depends on the engraving type: dust engravings almost never work, carved only seldom, burnt or graffitied offering the best chance.

Engravings are visible from a distance, having their own glyph which renders only when there is an engraving on top of “uninteresting” terrain (floor or corridor). In ASCII, they render as a “, or possibly a ~, but their color varies based on what type of engraving it is.

• Dust engravings: brown
• Actual engraving (e.g. athame): gray
• Burnt engraving: black
• Scrawl of blood: red
• Graffiti: bright green, bright blue, or bright purple

Put engravings outside or nearby inaccessible closets so that you know that something’s there.

Random piles of loot can sometimes generate buried in the floor or behind walls on spaces not adjoining any walkable spaces. Nearby engravings are generated to indicate that there is something in the vicinity. Archeologists get an alignment bonus for digging out these items.

You scuff engravings less when wearing elven boots because you are walking very quietly.

A role whose main mechanic is engraving and carving different magical runes on the ground.

Engraving (or ward) that is bad/cursed, and it causes bad things to happen on or around it. Anti-Elbereth of sorts. Monsters may deliberately engrave it to hurt the player.

Some means of leaving an engraving on the ground for the next player who reaches that floor to encounter (not a bones file, just a random engraving).

Vomiting erases any dust engravings on your current square.

Digging downwards destroys any existing engraving on the square.

Random engraving: “This ASCII tile was donated by [user].”, where user is either a name of someone that has contributed to nethack in real life, or just pulled from the high score list.

You can engrave on walls or doors. Elbereth on walls or doors doesn’t work. You can read it by standing on the nearest space. Random graffiti, if it generates on a floor square next to a wall or door, may say “Something is written on the wall here.” instead of the floor. Graffiti could render as ~ or something similar.

Engraving with Fire Brand should create a burnt engraving like a wand of fire does (it still degrades the sharpness of the blade, though).