Dexterity has a multitude of effects, of which the most significant is probably that it affects your chance of hitting monsters, whether in melee combat or with a missile or spell.
Intelligence is useful for reading spellbooks, for spellcasting (unless you are a Healer, Knight, Monk, Priest or Valkyrie, in which case it is wisdom that affects your chances of successfully casting a spell) and for encounters with foocubi. Mind flayers have a brain-eating attack that can drain your intelligence; if you are hit by a successful brain-eating attack when your base intelligence is already 3, you die of brainlessness.
Intelligence cannot be exercised, but can be permanently increased by drinking a blessed potion of enlightenment or a potion of gain ability. It can also be temporarily increased by wearing a helm of brilliance. If you eat a mind flayer corpse, there is a 50% chance your intelligence will be permanently increased by one point.
A Healer, Knight, Monk, Priest or Valkyrie requires wisdom to cast spells. Wisdom is not particularly important for most other classes, though it affects how fast your power regenerates (and is thus fairly important for wizards) and how much power you gain when leveling up.
Charisma is mostly useful for obtaining better prices at shops. It also helps with foocubus encounters, both by increasing the chance of a positive result and by giving more control over whether they remove your armor.
Charisma is a difficult stat to increase, as it cannot be exercised. It can be permanently increased by drinking a potion of gain ability, or temporarily increased by wearing a charged ring of adornment. You can also gain charisma by triggering a magic trap; however, this can be dangerous.
Reference: shk.c, line 1910.
First, points are distributed so that the player receives, as a minimum, the number indicated before the backslash. This is always out of a pool of 75 points, and the Remaining column contains the amount of leftover points from this step.
Next, the remaining points are distributed randomly according to the percentage after the backslash. If an attribute is chosen that would raise it above the player's racial maximum, it will try 99 more times to choose a different attribute to raise. If it fails to pick an attribute on all 100 attempts, it will abort this step and any remaining points will be lost.
Third, each attribute has a 5% probability of having a random number from −2 to +4 added to it . These respect racial maximums.
Finally, strength will, if necessary, be increased until the player is unencumbered by their starting inventory. If their racial maximum is not enough, constitution will be increased similarly.
These maxima only apply to your base "naked" attributes. Some magic items, like the helm of brilliance, gauntlets of power and gauntlets of dexterity, allow you to exceed these limits, up to 25 for all attributes. All attributes have a minimum of 3.
NetHack brass implements different maximum attributes per role. Find your maximum attributes by looking for your role in the next table, then applying the racial modifiers. For example, humans have +2 to strength. All heroes have a minimum of 3 for each attribute. The entries with the exclamation marks are the spellcasting stats for each role.
Reference: src/role.c in NetHack brass 040923.
To find your maximum attributes in NetHack brass, after finding your role in the above table, you must apply the racial modifiers of the below table. These racial modifiers apply only to the maximum attributes of each player, not the initial attributes.
An elven Ranger of NetHack brass, for example, can reach 19+1 = 20 in charisma by increasing charisma one more time after a human Ranger would have maxed at 19.
For strength modifiers only, a +1 raises 18 to 18/50, while a +2 raises 18 to 18/** or 17 to 18/50.
SLASH'EM handles several attributes differently compared to NetHack.
Due to the changed behavior of the gauntlets of power, strength between 18/** and 25 is handled differently. Strength grants bonuses to damage and to-hit as follows:
Reference: weapon.c in SLASH'EM 0.0.7E7F2, line 900.
Dexterity now has an impact on AC, and higher Dexterity provides bonuses to AC.
In FIQHack, strength over 18 is no longer considered a special attribute, and "exceptional strength" of 18/XX does not exist - their numeric equivalents are used instead, as follows:
- hit points
- Drain for gain, which involves manipulating your attributes, and discusses how to do so.