bone-343.txt  Last edited 2005-06-22 for NetHack 3.4.3
Leaving and loading bones files in NetHack 3.4
Compiled by Dylan O'Donnell <psmith@spod-central.org>

While NetHack is a single-player game, a certain amount of interaction
between games (and, on a multi-user system, between players) is provided
by bones files; levels on which a previous character has died being loaded
into a new game for a new character to encounter, complete with the ghost
of the former adventurer and their belongings (or indeed ghosts, since
bones levels can be themselves left as bones should you die there).

On any given system, only one bones file can be waiting at any time for
each distinct level. For this purpose, special levels are considered
distinct from normal ones; for example, an Oracle level at DL 6 can leave
bones despite the prior presence of a stored bones file for a regular
Dungeons level at that depth, and can be loaded in at a different depth if
that's where the Oracle happens to be located in the new game.


Leaving bones files
~~~~~~~~~~~~~~~~~~~
Some levels are ineligible to be saved as bones under any circumstances,
and should you die on these levels you will never leave a bones file:

Dungeons of Doom levels 1-3*              Medusa's Island
The Castle                                Gnomish Mines level 1 (maybe)**
Mines' End                                Sokoban (all levels)
Quest home and goal levels                Fort Ludios
Wizard's Tower top and bottom levels      Fake Wizard's Tower with portal
Vibrating Square level                    Moloch's Sanctum
Vlad's Tower top and bottom levels        Endgame (all levels)
Any level with a dungeon branch

* This is a consequence of the formula given below
** If at DL3, as a consequence of the formula given below

This means that the following levels are eligible to leave bones and have
bones files loaded for them (provided they don't contain the entrance to
another dungeon branch):

Dungeons of Doom (normal) DL 4+           Oracle
Big Room                                  Rogue Level
Gnomish Mines (normal) DL 4+*             Minetown
Quest locate and filler levels            Gehennom (normal)
Valley of the Dead                        Asmodeus' Lair
Juiblex' Swamp                            Baalzebub's Lair
Orcus-town                                Wizard's Tower middle level
Fake Wizard's Tower without portal        Vlad's Tower middle level

* Stored bones for Mines level 1 may be loaded at DL3, but not left
  at that depth.

If you die on a level that is eligible to leave bones and for which there
is not currently a bones file on the system, the chance of one being
created is dependent on the depth of that level: 1-(1/(1+(DL/4))) (note that
this, combined with NetHack's use of integer arithmetic, means that no level
above DL 4 will ever leave bones). The only other factor is that you will
not leave bones if you were swallowed or engulfed when you died; "Nothing
else. Not how you died, not what level you were, not what's in your
inventory, not whether it was loaded as bones, not any intrinsics or god
status or nearby monster." (from a Usenet article).

When bones are saved, you and your possessions are saved along with them,
along with the level layout, objects, and monsters. There are, however,
certain modifications made:

You leave a corpse, under most circumstances. If you were polymorphed and
unchanging, it will be that of your monster form (if that can leave
corpses); otherwise, it will be that of your race. No corpse will be left
if you are disintegrated, burned to death, die while unchanging and
polymorphed into a monster that does not leave corpses, or arise from the
dead as a different monster as detailed below. If you are stoned, you will
instead leave a statue containing your possessions.

If you leave a corpse, a grave is created (with the tombstone bearing your
character's name and manner of death) if the location is one where a grave
can occur (a non-trapped "floor of a room" square of open space).

You become a ghost, under most circumstances. If you died by sliming, you
instead arise from the dead as a green slime. If you were killed by any W,
you arise from the dead as a wraith; by any M, as a mummy of your race; by
any V and you are human, as a vampire; by a ghoul, as a ghoul. In each
case, the monster you arise as will be carrying your possessions. If you
are stoned, no ghost is created.

Items that were in your character's main inventory each have an 80% chance
of becoming cursed, if they weren't already. Items that were inside
containers are unaffected, whether the container is cursed or not.

Some monsters will never be saved in bones: the Wizard of Yendor, your
Quest Nemesis and Leader, Vlad the Impaler, and Medusa.


Loading bones files
~~~~~~~~~~~~~~~~~~~
When you first arrive at a level for which bones are eligible to be loaded
and for which a stored bones file exists on the system, there is a flat 1/3
chance that that file will be loaded.

The monsters on the level will have their peaceful status adjusted to suit
the character arriving there (for example, just because the dwarves and
gnomes on a Mines level were peaceful towards the dwarvish character that
died there, doesn't mean they'll be peaceful towards your orc who's found
those bones). In particular, this means that the previous character's pets
will often be found hostile. Monsters in the bones file that are extinct
or genocided in the new game will be removed.

Artifacts in the bones file that exist or have existed in the new game will
be converted to an ordinary non-artifact object of their type, as will the
Quest Artifact for the new character's role. The four Unique Items will
become normal items: the Amulet of Yendor a cursed cheap plastic imitation,
the Bell of Opening a cursed bell, the Book of the Dead a cursed blank
spellbook, and the Candelabrum of Invocation a number of cursed partly-used
wax candles corresponding to the number of candles (of any type) as had
been in the Candelabrum (at least one). Tins of unique monsters will become
empty.


Bones compatibility
~~~~~~~~~~~~~~~~~~~
Generally, bones files created by different versions of NetHack, or builds
on different platforms or with different compile options, will not be
compatible with each other. Bones created by a sufficiently similar build
of the same version on a sufficiently similar platform may be compatible
enough to be loaded; you can move them into place manually, or use a bones
exchange service such as Hearse (http://hearse.krollmark.com/).


Acknowledgements
~~~~~~~~~~~~~~~~
Corrections and clarifications provided by Kristoffer Björkman, John Cater,
Dayv, Jukka Lahtinen, and Spike.