Difference between revisions of "Mysterious force"

From NetHackWiki
Jump to navigation Jump to search
(some strategy)
m (History: Tense, word order)
 
(15 intermediate revisions by 6 users not shown)
Line 1: Line 1:
The much-maligned '''mysterious force''' is a random [[level teleport]]ation effect that occurs one quarter of the time{{refsrc|do.c|979}} when trying to climb stairs or using a [[BUC|cursed]] [[potion of gain level]] in [[Gehennom]] with the [[Amulet of Yendor]]. [[Lawful]] characters are dumped up to three levels below their current location; for [[neutral]] players it is up to two and for [[chaotic]] it is up to one.  (This includes occasionally being teleported around the level, a kind of "zero level drop".)  The mysterious force does not act when you go up from the [[Valley of the Dead]] to the [[Castle]], or when you enter [[Vlad's tower]] using the staircase. If you are inside the [[Wizard's Tower]], it will leave you on the same level if it would otherwise place you below the bottom of the tower.
+
In ''[[NetHack]]'', the '''mysterious force''' is a feature that occurs in various places:
  
Monsters (especially the [[Wizard of Yendor]]) may also be affected by the force when they try to flee upstairs with the amulet. Unlike the player, monsters will always be sent exactly one level down by the force and will be placed near the up staircase, and only if they aren't already in the three lowest levels of Gehennom.{{refsrc|muse.c|774}} Cursed potions of gain level will not trigger the mysterious force for monsters. These effects are summarized in the table below.
+
* [[Non-teleport level]]s will print the message "A mysterious force prevents <foo> from teleporting!" any time [[you]] or a [[monster]] attempts to teleport on that level.<ref>{{function|teleport.c|tele}}</ref>
 +
* Another "mysterious force" prevents you from descending the [[staircase]] on the [[quest home]] level without first getting permission from your [[quest leader]].{{refsrc|do.c|1018}}
 +
* While digging with a [[blessed]] [[pick-axe]] on the [[Plane of Earth]], a "mysterious force" may create a cave around you.<ref>{{function|dig.c|mkcavearea}}</ref>
 +
* If you are being escorted out of a [[vault]] and drop the gold on a square where the vault's walls used to be, a "mysterious force" will move it back into the vault when the walls are magically repaired.<ref>{{function|vault.c|wallify_vault}}</ref>
  
Despite a code comment in [[NetHack 3.4.3]] implying that the probabilities of each distance other than -1 are equal, this is not actually the case; the code actually randomizes the distance to move a player twice, leading to the following distribution:
+
This article describes the most relevant instance of the mysterious force for most players: a random [[level teleport]]ation effect that occurs while carrying the [[Amulet of Yendor]] in [[Gehennom]]. It is mostly known as the much-maligned primary obstacle that you face during the [[ascension run]].
 +
 
 +
==Description==
 +
When trying to climb up [[stairs]] or [[quaff]]ing a [[cursed]] [[potion of gain level]] in Gehennom with the Amulet of Yendor in your possession, the mysterious force will activate {{frac|4}} of the time and impede your progress.{{refsrc|do.c|979}} The mysterious force does not act when you go up from any of the four bottom levels of Gehennom, when you go up from the [[Valley of the Dead]] to the [[Castle]], or when you enter [[Vlad's tower]] using the staircase. If you are inside the [[Wizard's Tower]], it will leave you on the same level if it would otherwise place you below the bottom of the tower.
 +
 
 +
The mysterious force will often push you back by at least one floor; it can also teleport you around the same level as a kind of "zero level drop". You may also be sent back more than one floor depending on your [[alignment]]: [[Lawful]] characters are dumped up to three levels below their current location, while [[neutral]] players are dropped up to two floors below, and [[chaotic]] characters are the most fortunate, with a maximum of one level down.
 +
 
 +
Monsters, especially the [[Wizard of Yendor]], may also be affected by the force when they try to flee upstairs with the Amulet. Unlike the player, monsters that are not already in the three lowest levels of Gehennom will always be sent exactly one level down by the force, and will be placed near the up staircase.{{refsrc|muse.c|774}} Cursed potions of gain level will also not trigger the mysterious force for monsters. These effects are summarized in the table below:
  
 
{|class="prettytable"
 
{|class="prettytable"
Line 21: Line 31:
 
|}
 
|}
  
Later versions of NetHack did not change the formula, but did change the comments so that they described the formula correctly.
+
==Strategy==
 
+
Since [[Gehennom]] also contains many [[non-teleport level]]s, the player is advised to save a few cursed potions of gain level to bypass especially convoluted levels, such as [[Asmodeus' Lair]]. The annoyance that the mysterious force causes is enough for some to bring along or [[wish]] for a [[helm of opposite alignment]] in order to temporarily convert to chaotic alignment and avoid the worst of it, especially during [[speed ascension]]s using [[Dwarf (starting race)|dwarven]] [[Valkyrie]]s.
== Messages ==
 
 
 
{{message|A mysterious force momentarily surrounds you...|You were affected by the mysterious force and did not move up a level.}}
 
{{message|As <monster> climbs the stairs, a mysterious force momentarily surrounds <him>...|A monster carrying the amulet was affected by the force and moved to the previous level.}}
 
  
== Probabilities ==
+
There is an advanced strategy to bypass a few levels in the lower sections of Gehennom by taking the portal to the [[Wizard's Tower]], which typically moves you a few levels upwards (note that the force is less harsh inside the Tower). The strategy involves [[stoning]] the Wizard of Yendor when you first encounter him to obtain the [[Book of the Dead]], which as a [[unique item]] will not be trapped within his statue - you then return to the Tower during the run to the surface, [[stone to flesh|unstone]] him and toss him the Amulet. You can then escape the level via levelporting and meet the Wizard on the upstairs, and he should teleport to you with the Amulet.
  
How long does it take to escape the force? The following values are for a typical 22-level [[Gehennom]]. On average, Lawfuls take around 30% longer than Chaotics, and Neutrals take around 14% longer. Before the corrected probabilities were discovered, players used to believe that Lawfuls had a much harsher penalty when escaping Gehennom.
+
===Probabilities===
 +
{{upcoming|NetHack 3.7.0|The force has been changed to hit you less often proportional to the total number of levels you have been sent back already. Most of the calculations on this page will be invalidated.}}
 +
The following values are for a typical 22-level [[Gehennom]]. On average, Lawfuls take around 27% longer than Chaotics, and Neutrals take around 13% longer. Before the corrected probabilities were discovered, players used to believe that Lawfuls had a much harsher penalty when escaping Gehennom.
  
 
{|class="prettytable"
 
{|class="prettytable"
 
!            !! Lawful !! Neutral !! Chaotic
 
!            !! Lawful !! Neutral !! Chaotic
 
|-
 
|-
| Average staircase climbs (approx) || 45.2 || 39.8  || 34.9
+
| Average staircase climbs (approx) || 41.4 || 36.8  || 32.7
 
|-
 
|-
| Climbs for 90% chance of escape  || 63 || 53   || 43
+
| Climbs for 90% chance of escape  || 58 || 49   || 41
 
|}
 
|}
  
== Strategy ==
+
==History==
 +
The mysterious force first appears in [[NetHack 3.0.0]].{{refsrc|do.c|465|version=NetHack 3.0.0}}
  
Since [[Gehennom]] contains many [[non-teleport level]]s, climbing upwards would be annoying even without the force. The player is advised to save a few cursed [[potion of gain level|potions of gain level]] to bypass especially convoluted levels, such as the [[Asmodeus' Lair]].
+
Despite a code comment in [[NetHack 3.4.3]] implying that the probabilities of each distance other than -1 are equal, this is not actually the case - the code actually randomizes the distance to move a player twice, leading to the above distribution in the first table. The comments in later versions of NetHack have been changed to describe the formula correctly.
  
There's an advanced strategy to bypass a few levels in the lower Gehennom by taking the portal to the [[Wizard's Tower]], which typically moves you a few levels upwards (plus, the force is less harsh inside the Tower).  The troublesome part is escaping the Tower's top level: cursed gain level will not work, and the [[Amulet of Yendor|Amulet]] blocks [[levelport]]ing.  However, if you [[stoning|stoned]] the Wizard while obtaining the [[Book of the Dead|Book]] (as an unique item, the Book won't be trapped in the statue), you can now [[stone to flesh|unstone]] him, toss him the Amulet, escape the level via levelporting, and meet the Wizard on the upstairs.  He should teleport to you with the Amulet.
+
==Messages==
 
+
{{message|A mysterious force momentarily surrounds you...|You were affected by the mysterious force and did not move up a level.}}
== Variants ==
+
{{message|As <monster> climbs the stairs, a mysterious force momentarily surrounds <him>...|A monster carrying the amulet was affected by the force and moved to the previous level.}}
[[SLASH'EM]], [[SporkHack]], and [[UnNetHack]] have completely removed the mysterious force.
 
 
 
[[UnNetHack]] has, however, replaced the mysterious force with an effect that makes the Amulet of Yendor teleport itself whenever it is dropped for any reason.
 
 
 
== Other mysterious forces ==
 
 
 
A '''mysterious force''' is also cited as the reason that one cannot teleport on a [[non-teleport level]],<ref>{{function|teleport.c|tele}}</ref> or descend the [[staircase]] on the [[quest home]] level without first getting permission from your [[quest leader]].{{refsrc|do.c|1018}}
 
 
 
On some rare occasions, the mysterious force may take a more active role:
 
  
* While digging with a blessed pick axe on the [[Plane of Earth]], a mysterious force may create a cave around you.<ref>{{function|dig.c|mkcavearea}}</ref>
+
==Variants==
* If you're caught robbing a [[vault]], and drop the gold on a square where the vault's walls used to be, a mysterious force will move it back into the vault when the walls are magically repaired.<ref>{{function|vault.c|wallify_vault}}</ref>
+
[[SLASH'EM]], [[SporkHack]], [[UnNetHack]], [[xNetHack]], [[EvilHack]], [[SpliceHack]], and [[GruntHack]] have completely removed the mysterious force. UnNetHack, xNetHack, EvilHack, SpliceHack, and GruntHack compensate for this by making carrying the Amulet block all teleportation, including intra-level.
  
 +
UnNetHack and EvilHack also include an effect that can make the Amulet of Yendor teleport itself to a random location on the current level whenever it is dropped for any reason. The odds of it teleporting away depends on its BUC status.
  
 
==References==
 
==References==
 
 
<references/>
 
<references/>
 
+
{{nethack-366}}
{{stub|History, commentary, etc.?}}
 
 
[[Category:Strategy]]
 
[[Category:Strategy]]
[[Category:Religion]]
 
{{nethack-361}}
 

Latest revision as of 15:19, 15 September 2022

In NetHack, the mysterious force is a feature that occurs in various places:

  • Non-teleport levels will print the message "A mysterious force prevents <foo> from teleporting!" any time you or a monster attempts to teleport on that level.[1]
  • Another "mysterious force" prevents you from descending the staircase on the quest home level without first getting permission from your quest leader.[2]
  • While digging with a blessed pick-axe on the Plane of Earth, a "mysterious force" may create a cave around you.[3]
  • If you are being escorted out of a vault and drop the gold on a square where the vault's walls used to be, a "mysterious force" will move it back into the vault when the walls are magically repaired.[4]

This article describes the most relevant instance of the mysterious force for most players: a random level teleportation effect that occurs while carrying the Amulet of Yendor in Gehennom. It is mostly known as the much-maligned primary obstacle that you face during the ascension run.

Description

When trying to climb up stairs or quaffing a cursed potion of gain level in Gehennom with the Amulet of Yendor in your possession, the mysterious force will activate 14 of the time and impede your progress.[5] The mysterious force does not act when you go up from any of the four bottom levels of Gehennom, when you go up from the Valley of the Dead to the Castle, or when you enter Vlad's tower using the staircase. If you are inside the Wizard's Tower, it will leave you on the same level if it would otherwise place you below the bottom of the tower.

The mysterious force will often push you back by at least one floor; it can also teleport you around the same level as a kind of "zero level drop". You may also be sent back more than one floor depending on your alignment: Lawful characters are dumped up to three levels below their current location, while neutral players are dropped up to two floors below, and chaotic characters are the most fortunate, with a maximum of one level down.

Monsters, especially the Wizard of Yendor, may also be affected by the force when they try to flee upstairs with the Amulet. Unlike the player, monsters that are not already in the three lowest levels of Gehennom will always be sent exactly one level down by the force, and will be placed near the up staircase.[6] Cursed potions of gain level will also not trigger the mysterious force for monsters. These effects are summarized in the table below:

Level change Lawful Neutral Chaotic Monsters
​−1 75.00% 75.00% 75.00% 75.00%
0 6.25% 8.33% 12.50% 0
+1 11.45% 12.50% 12.50% 25.00%
+2 5.20% 4.17% 0 0
+3 2.08% 0 0 0
Avg. Change -0.470 -0.542 -0.625 -0.5

Strategy

Since Gehennom also contains many non-teleport levels, the player is advised to save a few cursed potions of gain level to bypass especially convoluted levels, such as Asmodeus' Lair. The annoyance that the mysterious force causes is enough for some to bring along or wish for a helm of opposite alignment in order to temporarily convert to chaotic alignment and avoid the worst of it, especially during speed ascensions using dwarven Valkyries.

There is an advanced strategy to bypass a few levels in the lower sections of Gehennom by taking the portal to the Wizard's Tower, which typically moves you a few levels upwards (note that the force is less harsh inside the Tower). The strategy involves stoning the Wizard of Yendor when you first encounter him to obtain the Book of the Dead, which as a unique item will not be trapped within his statue - you then return to the Tower during the run to the surface, unstone him and toss him the Amulet. You can then escape the level via levelporting and meet the Wizard on the upstairs, and he should teleport to you with the Amulet.

Probabilities

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

The force has been changed to hit you less often proportional to the total number of levels you have been sent back already. Most of the calculations on this page will be invalidated.

The following values are for a typical 22-level Gehennom. On average, Lawfuls take around 27% longer than Chaotics, and Neutrals take around 13% longer. Before the corrected probabilities were discovered, players used to believe that Lawfuls had a much harsher penalty when escaping Gehennom.

Lawful Neutral Chaotic
Average staircase climbs (approx) 41.4 36.8 32.7
Climbs for 90% chance of escape 58 49 41

History

The mysterious force first appears in NetHack 3.0.0.[7]

Despite a code comment in NetHack 3.4.3 implying that the probabilities of each distance other than -1 are equal, this is not actually the case - the code actually randomizes the distance to move a player twice, leading to the above distribution in the first table. The comments in later versions of NetHack have been changed to describe the formula correctly.

Messages

A mysterious force momentarily surrounds you...
You were affected by the mysterious force and did not move up a level.
As <monster> climbs the stairs, a mysterious force momentarily surrounds <him>...
A monster carrying the amulet was affected by the force and moved to the previous level.

Variants

SLASH'EM, SporkHack, UnNetHack, xNetHack, EvilHack, SpliceHack, and GruntHack have completely removed the mysterious force. UnNetHack, xNetHack, EvilHack, SpliceHack, and GruntHack compensate for this by making carrying the Amulet block all teleportation, including intra-level.

UnNetHack and EvilHack also include an effect that can make the Amulet of Yendor teleport itself to a random location on the current level whenever it is dropped for any reason. The odds of it teleporting away depends on its BUC status.

References