Precision
Precision or chance to hit determines chance of an attack hitting its target and the precision of area of effect attacks.
Basics
Precision is based on attacker's weapon skill against defender's defense skill and a large number of other factors. Precision is calculated the same way for both the player character and all non-player characters. Your precision is displayed on the right side of the attack cursor.
- Precision limits are 10—95% for targeted attacks, 15—90% for AoE attacks (such as grenades).
- AoE attacks targeted right at your feet or adjacent tiles will always have 100% chance to hit.
- Area of effect attacks can land up to 3 tiles away from targeted location. Thus, area of effect attacks with radius of 3 or greater will hit at least the primary tile they're targeted at even on a miss.
- Base precision (with equal attack and defense skills, no other modifiers) is 70%.
- Most psi attacks always hit their target. However, Pyrokinesis are Cryokinetic Orb are AoE attacks. Their precision is derived from Metathermics skill.
Modifiers
Precision is affected by many different modifiers, especially in ranged combat. Many of the precision penalties cannot be mitigated with weapon skill alone.
Skill
Attacker's and defender's skills are the base factors in hit chance calculation.
- Attack skill
- Increases precision, helps counteract defense skill effect.
- Defense skill
- Evasion can lower chance to hit down to 40% if evasion rating is twice the attacker's effective attack skill. Other factors in ranged combat can further lower hit chance down to 10%.
- Dodge can lower chance to hit down to 10% if dodge rating is thrice the attacker's effective attack skill.
- AoE attacks cannot be completely avoided with defense skill, but evasion decreases their damage up to 85%.
Environment
Environmental modifiers affect chance to hit in ranged combat.
- Darkness
- Darkness plays a large role in ranged weapon precision. Most areas in Underrail are dark and the penalty is quite high, especially at long ranges.
- Darkness penalty can be completely counteracted with Night Vision, or lowered with flares, fire and/or other ambient light sources.
- Certain critters have darkvision, allowing them perfect vision in darkness.
- Distance and optimal range
- Precision decreases with distance for all ranged weapons including AoE weapons.
- Precision further decreases beyond weapon's optimal range.
Weapon
Weapons can have additional modifiers to precision.
- Low durability
- Any Degraded Weapon or Heavily Degraded Weapon loses more precision the more degraded it is, all the way down to the minimal 10% chance to hit.
- Move and Shoot penalty
- Crossbows and rifles may have move penalty which decreases their precision if the user is not Focused. (Has moved during the current turn)
- Close Quarters penalty
- Crossbows and rifles may also have a precision penalty when foes are at melee range. Close quarters penalty only applies In Combat against hostile targets.
- Strength requirement
- Long guns and heavy melee weapons have a strength requirement. If the requirement is not met, precision is multiplied by current strength divided by required strength.
- Other weapon modifiers
- Weapons may have attachments or other modifiers that change their base precision or burst precision.
Vehicle
When attacking from a vehicle, the hit chance is multiplied by the vehicle's Stability.
Calculation order
This calculation varies slightly between melee, ranged and throwing weapons. This example is for ranged weapons.
First, the basic hit chance is calculated with skill modifier * lighting modifier * range modifier + weapon precision bonus and limited between the min/max values of 10% and 95%.
Next, the following additive modifiers are added:
- Weapon hit chance modifiers
- Weapon low durability penalty
- Weapon Close Quarters penalty
- Weapon Move and Shoot penalty
- Weapon Strength requirement penalty
- Weapon skill requirement penalty
- Expert Evasion veteran feat E
- Precognition psi ability E
Then the hit chance is again limited between 10% and 95%.
Finally, if the attacker is in a vehicle, the hit chance is multiplied by vehicle stability percentage.
External links
- http://underrail.info.tm/junk/precision.html — A simple calculator showing attack/defense skills required to attain certain hit/miss chances.