Huh I forgot about how a battle goes down.
Battles are turn based, 1 round is 10 segments (basically they represent seconds in the game's time). Actions have certain lengths which can be expressed in turns and segments, they cost that much time to perform.
Every round starts with Initiative Rolls. Everyone participating (PCs and the KM for the NPCs) rolls with d10 then adds this to the Initiative Value every character has. The highest starts with an action. An action can be an attack or any other activity (most likely battle related, like moving, casting a spell, drinking a potion or such). Initiative rolls are omitted in situations when it's clear who starts, for example at ambushes.
For attacking a character have to make an Attack Roll with d100 and add this to his(/her) Attack Value. An Attack Value consists of the character's full Attack Value (base + skills + weapon) and Situation Modifiers. If the Attack Value + d100 is > the targeted character's Defense Value ([base + skills + weapon] + Situation Modifiers) then it's a hit and Damage Roll comes.
Damage calculation: weapon's damage (e.g. d6+2) + attacker's Strength Modifier (if any) - defender's Armor Rating (if any). The Damage then is subtracted from the Pain Points first, if the Pain Points get to 0 or below then the character passes out and further damage is subtracted from the Health Points. Health Points can be reduced directly with Overkill. If the Attack Roll + Attack Value > Defense Value by 50 or the roll is exactly 100, then it's an Overkill and the damage will reduce HP's. Every HP lost comes with doubled PP reduction as an extra.
The attacks follows each other in the order established in the beginning of the round. Some characters can have more than one attacks if their weapons and skills and such allow this.
Ranged weapons use Targeting Value ([base + weapon + skills] + Situation Modifiers) instead of Attack Value for attacks and the Defense Value is equal to the range and can be modified by the situation ofc (does the target moves? etc.). Ranged fighting has the Archer Rule. When you roll damage and get max score you can roll again, and repeat as many times as you roll max. Players came up with a neat little trick. The rulebook describes a magic item, the Lucky Coin which gives +1 to every roll. In the world the player can make or pay someone to make a ranged weapon with d2 Damage. With the Lucky Coin if you roll 1 on d2 it counts as 2 which is the max score on d2 hence you can roll again and again and again... instakill everything... with a d2 weapon.
Situation Modifiers: attacking from behind, attacking from semi-behind, ambush, from height advantage (not the height of the body but from a higher place), from height disadvantage, from moving horse, when blind or in pitch dark, in semi-darkness, when stationary, when laying down, when dizzy, when paralyzed, when frightened, with full of hatred, storming, concentrating on defense, with the intent of capturing the enemy.
It's much detailed ofc but that's about it. Too many calculations if you ask me.