Neverwinter Nights has five difficulty settings that the player (in single player) or the server owner or DM (in multiplayer) can set. Players can access the setting in the options menu and the DM client has a slider to adjust it.
The initial setting used when the game starts is stored in nwnplayer.ini, the "Difficulty Level" setting in the "[Game Options]" section.
The details of each setting are defined in (and can be changed via) diffsettings.2da.
In addition, specific modules may adjust to the difficulty setting via scripting. (For example, there is an encounter in the Hordes of the Underdark campaign where custom AIs are used, and those AIs improve at "hardcore" and higher.)
Differences from the next-easier difficulty are marked in bold face.
Very easy
- Single player: No PvP (Fireballs and other area effect spells will not harm party members.)
- Multiplayer: As per server setting.
- No critical hits on PCs.
- No attacks of opportunity on players using ranged weapons.
- No attacks of opportunity on players using potions.
- PC does a minimum of 100% of damage.
- NPC does a maximum 25% of damage.
- Players cannot die.
- Sleep (spell) on players lasts for a short (quartered) duration.
- Domination and charm effects will daze a player.
- Hold, paralyze and stun effects will daze a player.
- Confusion effects will daze a player.
- Fear effects will cause a -2 penalty to hit.
- Petrification (such as from the flesh to stone spell) lasts for one round per caster level.
Easy
- Single player: No PvP (Fireballs and other area effect spells will not harm party members.)
- Multiplayer: As per server setting.
- No critical hits on PCs.
- No attacks of opportunity on players using ranged weapons.
- No attacks of opportunity on players using potions.
- PC does a minimum of 50% of damage.
- NPC does a maximum 50% of damage.
- Players can die.
- Sleep spell on players lasts for a short (quartered) duration.
- Domination and charm effects on players will daze a player.
- Hold, paralyze and stun effects on players last for a short duration.
- Confusion effects on players function normally.
- Fear effects on players will give them a -4 penalty to hit.
- Petrification lasts for one round per caster level.
Normal
- Single player: No PvP (Fireballs and other area effect spells will not harm party members.)
- Multiplayer: As per server setting.
- No critical hits on PCs.
- No attacks of opportunity on players using ranged weapons.
- No attacks of opportunity on players using potions.
- PC damages normally.
- NPC damages normally.
- Players can die.
- Sleep spell on players last for a short (halved) duration.
- Domination and charm effects on players cause daze.
- Hold, paralyze and stun effects on players last for a short duration.
- Confusion effects on players function normally.
- Fear effects on players function normally.
- Petrification lasts for one round per caster level.
D&D hardcore rules
- Single player: Full PvP (Fireballs and other area effect spells will hurt party members.)
- Multiplayer: As per server setting.
- Critical hits on PCs.
- Attacks of opportunity on players using ranged weapons.
- Attacks of opportunity on players using potions.
- PC damages normally.
- NPC damages normally.
- Players can die.
- Sleep spell on players functions normally.
- Domination and charm effects on players cause daze.
- Hold, paralyze and stun effects on players function normally.
- Confusion effects on players function normally.
- Fear effects on players function normally.
- Petrification is permanent.
Very difficult
- Single player: Full PvP (Fireballs and other area effect spells will hurt party members.)
- Multiplayer: As per server setting.
- Critical hits on PCs.
- Attacks of opportunity on players using ranged weapons.
- Attacks of opportunity on players using potions.
- PC damages normally.
- NPC weapons do 200% maximum base damage. (e.g. 1d10 becomes 1d20)
- Players can die.
- Sleep spell on players functions normally.
- Domination and charm effects on players cause daze.
- Hold, paralyze and stun effects on players function normally.
- Confusion effects on players function normally.
- Fear effects on players function normally.
- Petrification is permanent.