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.

It is possible to leave bones on Astral. If this happens, instead of a ghost, there will be a fourth resurrecting Rider, War, with all the equipment of the dead player, 100% of it cursed.

Ghosts (and technically other player remnant monsters such as wraiths, ghouls, etc) found in bones levels are empowered with additional abilities that normal monsters don’t have.

If you die to overwhelming cold damage (on the order of 3-4 times your current HP, for instance from Asmodeus’s cold attack), you leave behind a frozen statue (made of ice?) instead of a corpse.

Ghosts left behind by coaligned players are peaceful and grudge against hostile-to-the-player monsters. Ghosts killed by brainlessness do not behave like this, nor do ghosts not generated with bones.

Track how often bones files from a player are loaded. Because multibones levels exist, this should probably be accomplished by exposing in the discoverer’s dumplog or xlogfile every instance of a struct cemetery existing in the game, specifically the name of the player associated with it.

Alternate ending where you can settle down in an abandoned temple or possibly just a random altar room and become the priest of the temple permanently. (Creating a bones file where you are now an aligned priest).

Bones files created from filler levels should treat themselves as being on the deepest level the player reached in that branch in their game, so that there aren’t situations where a character carrying good gear who died in a silly manner on a higher-up level will leave a bunch of accessible loot.

Occasionally, when a bones file would create a ghost (e.g. most times), and the level difficulty is high enough, create a wraith of the player instead. If in Gehennom, occasionally create a shade of the player.

When the player is killed by a carnivorous (or, more rarely, an omnivorous) monster, the bones file may not contain a corpse because it was eaten by the monster. Never happens if it would be cannibalism for the monster to eat you.

Make bones a composite option that enables you to load only your own bones files, and never other people’s.

Bones levels have a special level sound. Possibly the same “eerie feeling” you get in abandoned temples.

When a monster triggers a magic (or maybe polymorph) trap, one possible effect is that they turn into a figurine of themselves with appropriate beatitude. However, the trap exploding on them is more likely, so that it can’t be used to farm figurines. A possibly evil addendum is that if the player would have otherwise died from damage from a magic trap, the bones file may contain a figurine of them instead of a corpse.

Restrict bones files from being loaded (possibly just discarding the bones file) if they contain monsters that are far out of difficulty for the player encountering them.

Make it possible to leave bones on certain levels that have a branch entrance in them (mainly mine entrance, sokoban entrance, quest), by virtue of removing the branch entrance before saving it as bones. If branch upstairs are removed in this manner, replace it with a pile of rocks; if downstairs are removed in this manner, replace them with a pit.

Alter the player’s corpse weight based on how hungry they were when they died.

The player’s own ghosts generate peaceful (possibly only in bones files).

Various ideas to prevent powerful bones generated on a level’s upstairs from instakilling a player:

• Don’t generate bones if the player died on the upstairs.
• Going downstairs doesn’t use a turn, but going up does.
• When saving the bones, set all monsters’ movement points to 0.
• If the player died on the upstairs, swap the upstairs and downstairs locations.
• A way to “peek” up or down the stairs without going there.

Bias the probability of bones files to be a general bell curve fixed on around level 10-15.