Blindness

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Blindness is a property that appears in NetHack, and blocks the ability of a hero or monster to see their surroundings.

The zen conduct consists of playing the entire game with a permanently blind hero.

Description

A hero or monster that is blind cannot see for the duration of the property—messages describing actions such as monster-versus-monster-combat that the hero cannot see are omitted or else significantly altered.

Intrinsic blindness is defined as "blinded" in youprop.h.[1] The game records the number of turns that a hero is blinded. There are also a few attacks that have the "blinding" damage type, which is represented by the AD_BLND flag in monattk.h:[2]

A hero that cannot currently see due to their form or a worn item is defined as "blind" in youprop.h.[3] This form of blindness is considered "permanent" in that it will persist until the source of the blindness is removed. Blindness of this type occurs from the following sources:

In addition to the above, the following circumstances and items can result in a hero being blinded:

Blindness resistance blocks light-based sources of blindness, and being blinded will prevent further blinding from most other sources (with exceptions including the potion of blindness). A blind hero cannot use gaze attacks, and is unaffected by gaze attacks that require the target to see its user.

Creamed

Being "creamed" is a subset of blindness that results from a substance over the hero's eyes physically restricting their vision.[8] The game records the number of turns that a hero is creamed.

Sources of creaming increment the number of turns that the hero is creamed and blinded by the same amount, so its duration is always less than or equal to the number of turns that the hero is blinded - this also means that the "creamed" status will always time out first, e.g. a hero that is blinded for 100 turns, and 50 turns later becomes creamed for a duration of 20 turns, will be blinded for a total of 70 more turns; during the first 20 of those turns, they are considered creamed.

The following actions can result in a hero being creamed:

Blind from birth

Main article: Zen

Playing a zen hero via the blind option makes them "blind from birth". This blindness persists across any forms that the hero polymorphs into and cannot be cured, though wearing The Eyes of the Overworld cures its effects and breaks the conduct—see the section on astral vision below for more details of the property's effects on blindness.

The following information pertains to an upcoming version (NetHack 3.7.0). If this version is now released, please verify that the information below is still accurate, then update the page to incorporate it.

Wearing The Eyes of the Overworld does not remove zen-blindness—it will still suppress its effects while worn, but taking them off will leave a zen hero blind again.

Blind monsters

Monster blindness is handled differently from a hero's blindness: monsters that have eyes can be blinded by most of the same means as the hero, while a monster without eyes is intrinsically blind and cannot be blinded by other means.

A blind monster will move and attack erratically, and suffers a to-hit penalty. Blinded monsters do not respect Elbereth if they would have normally, and cannot use any gaze attacks they possess.

Blind movement

When a blind hero is moving normally, or else using near look via : or picking up items via ,, they will automatically use their hands to feel for items on the ground. Touching the corpse of a cockatrice or chickatrice this way will petrify the hero unless they are wearing gloves. Safe-moving via m will ignore objects on the ground.

A blind hero moving onto a seemingly empty square with a monster on it will show the monster as I, anger them if they were peaceful, and use up a move without attacking even while safe-moving via m.[9] Moving into a square with an I or warning symbol will cause the hero to automatically attack in that square's direction—safe-moving via m will function as normal if a monster is occupying the square, or move into the square normally if it is empty. A blind hero safe-moving with m into an unseen footrice without wielding anything or wearing gloves will turn to stone as well, unless the footrice's position is marked by the warning property.

It is still possible for a hero to sense their surroundings through other means while blind:

  • Searching manually via s will use a move and attempt to reveal the location of adjacent, unseen monsters if there are any nearby—monsters detected this way have the square they occupied at the time of searching marked with a I. If searching this way does not detect a new unseen monster, it will reveal all squares adjacent to the hero, clearing any existing invisible monster markers on squares where none are present.
  • A hero that has intrinsic or extrinsic telepathy can detect all non-mindless monsters on the level while blind, and interactions with these monsters are handled normally, both for normal movement and safe-moving via m.
  • Monster detection obtained from quaffing a blessed potion of monster detection or casting the detect monsters spell at Skilled or higher allows the hero to track all monsters on the level for the duration of the effect, and those monsters are handled normally for purposes of movement.
  • Movement involving monsters highlighted via warning functions as normal, since warning does not rely on the hero's sight.

Blindness and items

While blind, most unidentified objects are described only by object class (e.g. "a potion", "a ring", "a long sword" etc.), including artifacts—only amulets and comestibles are treated as "seen" while blind. A hero that starts the game blind (i.e. from birth) will know the appearance of their starting inventory, as well as that of their pet (which in practice only applies to zen Knights).[10][11] A blind hero will also always know the appearance of eggs that they laid themselves.[12]

The poisoned and erosion status of weapons are still shown if the hero becomes blind, and erosion-proofing and charges are only shown for an item once it is formally identified, even if it was erosion-proofed while blind. Any dilution in potions is only displayed if the hero knows that potion's appearance. A blind hero that polymorphs any known object, fully dilutes known potions, or performs alchemy with them will render those items unseen.

A blind hero cannot name the object class of unidentified objects, and any individual names will not be displayed, though they will affect stacking and naming artifacts. Blind heroes can still hear monsters reading the label of a scroll or quaffing a potion, but will not auto-identify them since they cannot see the result.

Buying or selling something directly at a shop while blind will have the shopkeeper identify its appearance unless the item is in a container, and this is naturally not applied to merchandise that was stolen or covered by a hero's credit should the hero leave without paying.[13]

If a blind hero attacking with Vorpal Blade or The Tsurugi of Muramasa causes the beheading or bisection special attack to trigger, the artifact's appearance will be revealed.[14][15][16][17] Eating a tin from a stack of tins while blind will identify the contents of remaining tins in that stack.

Curing blindness

"Creamed" blindness can be cured by using the #wipe extended command, applying a non-cursed towel or praying successfully.

Temporary blindness that is not from the hero's current form, a worn item, being "creamed", or the hero being born blind can be removed with the following actions:

If the hero is blind due to a worn towel or blindfold and it is not cursed, they can simply remove it - a cursed blindfold or towel will require uncursing in order to remove, and is considered a major trouble for prayer purposes. A hero that is polymorphed into an eyeless form and not blinded from any other source will regain sight upon changing into a form with eyes (including returning to normal form).

Astral vision

Main article: Astral vision

While astral vision does not cure blindness on its own, The Eyes of the Overworld both grants the properties and suppresses blinding effects, allowing the hero to see in spite of it—they can view and interact with monsters in the sight radius as normal, and items seen within that radius are treated as though the hero had seen and handled them personally. As temporary blindness is still applied even while suppressed, it will time out as normal while printing different messages.

Strategy

Blindness can be fairly debilitating in the early stages of the game, especially if a magic trap blinds the hero and hems them in with several hostiles. While many forms of blindness that obstruct a hero are usually temporary, waiting them out can be dangerous without an alternate means to view the hero's surroundings—this typically makes floating eyes a priority target for the telepathy their corpses grant, and a hero that can temporarily blind themselves "at will" can also handle floating eyes very easily. Gaining the intrinsic early on and keeping backup sources on-hand will make being blinded very manageable.

Unicorn horns are among the most accessible cures for blindness that any character can use, and as long as the horn is kept non-cursed, being blinded unexpectedly becomes a short and manageable nuisance at most.

Navigating while blind

While keeping still to wait out temporary blindness is not always feasible, moving while blind requires significant care, due to the massive amount of complications introduced:

  • Nearby peacefuls and pets may end up hit if you attack blindly, since you cannot see if they stepped into any square previously occupied by a hostile monster (or killed the hostile themselves, in the case of a pet)—being blinded in Minetown or a shop can result in a swift and unceremonious death at the hands of a shopkeeper or the watch.
  • Allowing hostile monsters to attack the blinded character first is incredibly risky—even if you attack the specific square you were hit from, the monster may be fast enough that it can briefly wander away after attacking; at best, this results in a wasted turn attacking the I where they previously were.
  • Levels with cockatrices have a long-term threat of instadeath: if one is killed and leaves a corpse, touching it without gloves while feeling around for objects will immediately render the hero a statue.
  • The bloodthirsty Stormbringer is made even more dangerous to wield than usual.

Searching to reveal inhabited squares and then safe-moving into them with m is generally recommended: the game also prints different messages for safe-moving depending on if you moved into a peaceful/tame monster ("Pardon me, <foo>.") or a hostile one ("You move right into <foo>."), and those messages are unchanged for a blind hero. A stethoscope can be applied for free once per turn to determine if something is in your path and it is unsafe to move there—in rare cases, chatting is also useful to test for non-silent monsters, since it does not use up an action if you get no response.

Telepathy and warning are the best properties to have in case you are blinded, since warning complements telepathy by revealing the positions of most mindless monsters: while even these properties combined will not reveal all possible monsters, the few mindless monsters that are not revealed by warning are generally not a threat at most points where you have access to both. (Further corner cases stem from hiding monsters, cloaked mimics, Stormbringer, F, and deactivating safe_pet.)

Reading a scroll of magic mapping whose label or identity is known, or else casting the magic mapping spell, will reveal the layout of the entire level, which can be a time saver and even a life-saver in some circumstances.

Avoiding blindness

For the property that blocks blindness from certain sources, see blindness resistance.

On top of the listed means of curing blindness, there are also ways to prevent some or all sources of blindness:

  • Wielding Sunsword protects the wielder from light-based sources of blindness, including yellow lights, magic traps and wands of lightning.[19]
  • Wearing a blindfold or towel can protect from blinding gazes and some other sources such as blinding attacks, but it will not prevent blindness from quaffed or thrown potions.
  • As explained above, astral vision granted from The Eyes of the Overworld circumvents blindness.

Discovering objects

In addition to the listed forms of identifying items while blind above, there are other methods to identify objects while blind which are non-exhaustively listed below:

Zen strategy

Main article: Zen conduct strategy

Playing a permanently blind hero requires awareness of much of the above considerations and details alongside knowledge specialized to the conduct. See the provided link for further details on how to manage zen play.

History

Blindness as a status property exists in Hack 1.21 and Hack for PDP-11, which are based on Jay Fenlason's Hack, and also appears in Hack 1.0.

Messages

Wait! There's something there you can't see!
You moved onto a seemingly empty square. This does not attack whatever monster was on that square, but does anger them if they were peaceful.

References

  1. ↑ include/youprop.h in NetHack 3.6.7, line 85
  2. ↑ include/monattk.h in NetHack 3.6.7, line 48
  3. ↑ include/youprop.h in NetHack 3.6.7, line 85
  4. ↑ src/mcastu.c in NetHack 3.6.7, line 576
  5. ↑ src/mcastu.c in NetHack 3.6.7, line 663
  6. ↑ src/apply.c in NetHack 3.6.7, line 1929
  7. ↑ src/region.c in NetHack 3.6.7, line 975
  8. ↑ include/you.h in NetHack 3.6.7, line 331
  9. ↑ src/uhitm.c in NetHack 3.6.7, line 143
  10. ↑ src/u_init.c in NetHack 3.6.7, line 1082
  11. ↑ src/dog.c in NetHack 3.6.7, line 192
  12. ↑ src/sit.c in NetHack 3.6.7, line 319
  13. ↑ src/shk.c in NetHack 3.6.7, line 2562
  14. ↑ src/artifact.c in NetHack 3.6.7, line 1275
  15. ↑ src/artifact.c in NetHack 3.6.7, line 1292
  16. ↑ src/artifact.c in NetHack 3.6.7, line 1322
  17. ↑ src/artifact.c in NetHack 3.6.7, line 1338
  18. ↑ src/apply.c in NetHack 3.6.7, line 2043
  19. ↑ src/mondata.c in NetHack 3.6.7, line 146
  20. ↑ src/detect.c in NetHack 3.6.7, line 582: object_detect
  21. ↑ src/zap.c in NetHack 3.6.7, line 496
  22. ↑ src/zap.c in NetHack 3.6.7, line 1922
  23. ↑ src/zap.c in NetHack 3.6.7, line 2964
  24. ↑ src/quest.c in NetHack 3.6.7, line 123
  25. ↑ src/quest.c in NetHack 3.6.7, line 227
  26. ↑ src/quest.c in NetHack 3.6.7, line 241
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