The most common action in Algorion is simply attacking with weapons. The bulk of the populace are not monsters, and cannot cast spells, and thus rely on their proficiency with weapons, implements and unarmed attacks to defend themselves.
Attacks come in 2 Flavors: Melee Attacks, and Ranged Attacks. Most of the rules are the same for both, and it will be noted where they are different.
Attack rolls determine if your attack hits or misses a target. Note that attack rolls are abstract. Missing an attack might not mean that you missed with a weapon attack. It could mean that your opponent parried it, or that it glanced off their armor or scales, or didn't do a significant enough blow that grit damage was scored.
Regardless of how you view it, attack rolls are the same. Roll a d20, add modifiers and compare the result to the targets AC. If your attack roll is greater than or equal to the target's AC, you score a hit, and deal damage. If your attack roll is less than the targets AC, your attack does not deal damage.
There are common Modifiers that alter your Attack Roll.
When you make an attack with a melee weapon, or you throw a melee weapon, you use your Strength Modifier.
When you make an attack with a range weapon, or a weapon with the Finesse Weapon Property, you use your Dexterity Modifier.
You apply your full Offence Bonus to attack rolls, when you make attacks with a weapon for which you have proficiency with. When you attack with a weapon that you are not proficient with, you do not apply your offence bonus.
Sometimes, you just get lucky (or unlucky) in combat. If the result of your d20 dice roll is a 1, you miss your attack, regardless of the AC you would have hit. If your roll is instead a 20, you may have a chance to critically hit! Critical hits are covered under Damage.
Creatures who are hiding, creatures who are invisible, or creatures just outside of your torchlight are all unseen. When you are attacking a creature who is unseen, you must attempt to guess their location, then make an Attack Roll with a -5 situation. If the creature is not where you guessed they were, your attack automatically misses, but the GM will simply tell you that the attack missed, not if you guessed the right location or not.
When you attack a creature that cannot see you (but they are aware of you), you gain a +2 situation to your attack roll. If the creature isn't aware of you either, increase this to +5 situation.