This spoiler explains the changes to the game induced by a player's choice
to play in "nightmare mode". This can only be done at character birth
(see the documentation on start-up options) and is irreversable.
Nightmare mode is designed to be unfair and is not intended to be
winnable although very competent players may be able to do so. Players
who take up the challenge of nightmare mode will have their score
increased by a significant factor.
Some of the changes induced by nightmare mode are very obvious to the
player while others are much more subtle.
=== What does nightmare mode do? ===
--- Player ---
1. Golems lose their immunity to stunning.
2. Spectres lose their immunity to nether (but still resist it).
3. Vampires can never resist light.
--- Monsters ---
1. The game disregards the player's choices as to whether or not to
switch on monster AI options and smart_cheat as well as both
monster-flow options are assumed to be in effect.
2. Monsters all start awake and can never be slept, scared or confused.
They cannot be stunned (except by Monks).
3. Monsters' hitpoints are doubled and each monster receives a bonus of
between 5 and 10 to their base speed.
4. Monsters gain a random chance of resisting a magical attack even if
they do not ordinarily have the required resistance.
5. Monsters with the "MULTIPLY" flag breed more quickly and the limit
of such monsters is increased from 100 to 255.
6. Monsters are more likely to be generated out-of-depth and in groups.
7. Monster corpses which are in the player's line-of-sight have a
random chance of being resurrected each turn.
8. Monsters' hitpoints regenerate more quickly.
9. Over time pets will become {friendly} and {friendly} monsters
will turn aggressive.
--- Objects ---
1. The maximum number of objects per level is reduced as is the chance
of objects being generated out of depth.
2. The scaled reduced energy for activating magical items is removed
so that it always takes a full turn to use them.
3. All positive timed effects have a 10% chance each turn of having the
remaining duration halved.
4. The failure rates for using magical items is increased by 5% for all
items.
5. Objects that grant "reflection" will let the attack through twice as
often.
6. Artifact recharge time is doubled and cursed artifacts can only be
successfully activated 5% of the time.
7. Pseudo-id will occasionally inscribe an item incorrectly.
8. Items which resist disenchantment are no longer immune to it but
still have a significant chance of resisting the effect.
Disenchantment has a small chance to also remove magical abilities
from an item.
9. Double resistance no longer protects items in your inventory from
being destroyed by that form of attack. Only immunity will provide
this.
10. Scrolls may occasionally have no effect when read.
--- Combat ---
1. Damage of monster spells and melee attacks is doubled. Monsters
never miss in melee and spells never fail.
2. Monsters get critical hits in melee more often.
3. Players get critical hits less often.
4. Bonuses from "Slays" are occasionally disregarded.
--- Magic ---
1. You can never get below 5% failure rate for spells although this is
a hidden limit.
2. There is a 1% chance that targetted spells and magical effects will
go in a random direction.
3. Ball spells initiated by the player will damage the player if he is
in their sphere of effect.
--- Town ---
1. Selection of shopkeepers is biased towards those with the lowest
purses. Shopkeepers never rotate.
2. Shopkeeper greed is increased by 20.
3. Shops are less likely to stock piles of an item and piles will be
smaller.
4. In the development version, towns are 50% further apart.
5. Your home may be robbed if you do not visit it at least once each
day.
6. Sleeping in the inn to avoid the midnight curse (see below) will
have various unpleasant side effects.
--- Wilderness and Dungeon ---
1. Terrains that can damage the player will do twice as much damage as
normal.
2. Traps are 50% harder to disarm and are more likely to be nasty.
3. The game occasionally creates both invisible walls and walls which
seem normal but are passable by both the player and monsters.
4. Greater vaults are half as likely. Random vaults are more likely.
Lesser vaults are unchanged.
--- Other ---
1. Mutations are more likely to be nasty.
2. You will be subjected to an invocation of the Ancient and Foul Curse
each midnight and randomly throughout the day.
3. The "Summon Cyberdemons" and "Paralyzation-with-Free-Action"
combination of the Ancient and Foul Curse is restored in all its
glory.
4. Temporary and permanent resistances are not cumulative.
5. Word of Recall will occasionally reset your recall depth to random
dungeon level.