The Atheian system is designed to be simple. It uses d20s, with (in general) high rolls being better. It is skill-based. Training skills provides bonuses to certain actions, depending on the skill. Attributes, a person's physical characteristics, are used to determine a base for certain skills, miscellaneous actions, and to flesh out aspects of a person's character.
There are four main attributes. These would be Strength, Intelligence, Reflexes, and Will. Your attributes can have a score of 1-19. The main reason for this is so that there is always a chance for failure and success when rolling against an attribute. The average score is a 10, with 19 being extraordinary and 1 being pathetic.
Each attribute has certain skills which it aids by giving them a base point total. For each point above 15 in your attribute, you increase the base point total in the skill by 1. For example, strength provides the climb skill a bass point total. A 15 strength gives you a +0 strength, a 16 strength a +1, a 17 strength a +2, and so on.
Strength is the measure of how strong you are. It deals more with bursts of speed rather than stamina. Short, single actions rather than lengthy ones. Its base skills would be climb, fighting (melee), and swim.
Intelligence relates to how smart you are, and how many skills you know. Increase or decrease your skill points by your intelligence modifier. So if you have an intelligence of 12, you have 2 more skill points to place. More on skills in a bit. It increases the base skill of Knowledge.
Reflexes deal with your speed and, well, reaction time. As such, they translate into your dodge potential. High reflexes means you can dodge attacks while, bad reflexes mean that you tend to be in the way of a sword. Thus, your reflex modifier is added to your AC (which will in explained in the Combat section). Its base skills would be stealth, and fighting (ranged).
Will is how stubborn you are, how determined you are. It deals with such things as stamina and lasting a long time in combat. Thus, it affects your health. Your Will score is taken and becomes your total hit points (HP). A Will of 13 means you have 13 HP. Its class skill is ride.
There are a grand total of two classes in the Atheian system. These would be Fighter and Rogue. FIghters focus on, well, fighting, and other combat related activities. Rogues can specialize in anything they choose, allowing them to be either diplomats or thieves, bards or backstabbers. Each class has three class skills. These skills are given an aid in skill point distribution. For each point you put into a class skill, you get a free 1/2 a point. So if you put two points into a class skill, you end up with three points.
Fighters, specializing in fighting, get Weapon Specialization as an added ability. At first level, the fighter can pick a class of weapons, such as axes, swords, polearms, bows, etc. First, they get a +1 to hit when wielding that weapon at first level. At second level, they get +1 damage when using that weapon. At third level, they increase their to hit chance with that weapon to +2. At fourth level, they increase their damage with that weapon to +2. At fifth level, the fighter can pick the same or a different class of weapons to repeat the process (with at fifth level you gaining a +1 to hit). Instead of a class of weapons, a fighter can choose either armor or shields, with alternating in the same manner between +1 AC and +1 damage resistance.
Rogues, instead, gain Knowledge Application. This allows a rogue to gain a bonus to whatever action they are currently engaged in equal to half the bonus of a Knowledge skill that applies. For example, if Sneakius the Sneaky wants to sneak his way past a group of guards in some grand cathedral, and he has the Knowledge (architecture) skill, then he can use that knowledge to know that cathedrals in this style tend to have niches along the sides to gain a bonus in his stealth check. As he has a +2 Knowledge bonus, he adds +1 to his Stealth roll.
Skills provide bonuses for certain actions, depending on the skill and the action. A person can put up to 100 skill points (SP) into a single skill. Every five points gives you a +1 when performing that skill. At five SP, you get a +1, at 10 you get +2, etc. For each use of a skill, the GM gives the PC a number, called the roll number (RN), that the PC has to roll to get. The PC rolls a d20, adds their bonuses, and if the number is equal to or higher than the RN, then the PC succeeds. If the GM so desires, he can make it so that just missing the RN grant limited success (you didn't jump across the chasm, but you're clutching to the side of it). The two fighting skills, magic, and spells will be described in more detail in other sections. The skills are:
climb: deals with traversing any manner of surfaces that are more vertical than horizontal. Too much weight can add negative bonuses to this skill: if you're wearing or carrying more weight than 10x your strength, then you roll a strength check every 10 feet you climb- failure gives you a -1 to your climb check and a +1 to your next strength check. These negative modifiers are additive, and each time you fail the check you add to your negative modifier.
communication: deals with persuasion, public speaking, anything that requires talking.
craft (player's choice): the PC can choose a type of object, and can attempt to craft it if he has any amount of skill points in craft.
fighting (melee): improves your ability to hit something with a close-ranged weapon, such as a sword or an axe. This also govern unarmed fighting.
fighting (ranged): improves your ability to hit something with a projectile weapon, such as a bow r a sling. This also governs throwing things.
heal: deals with first aid and such. Successful heal checks can slow poison, stop bleeding, cure disease, etc., as long as the necessary materials are nearby. If healing a wound, can restore 1d4-2 HP (negatives are treated as 0 for people who have some points in heal, and as regular negatives for people not trained).
knowledge (player's choice): training knowledge gives the PC more and more knowledge of a certain thing, which the PC can choose. When a PC encounters something that is related to his knowledge skill, he can roll to see if he knows it.
magic (domestimancy, necromancy, pugnamancy, telemancy, or vivamancy): used to determine if a magical affect hits the target (not required when using friendly magics on allies). Can be trained five different times, for each of the five schools of magic.
profession: can be used to determine a check for some action relating to your profession. For example, a bard might do a profession check to sing a song. The profession check can be used once a day to earn money as well: the actual earnings are determined by the profession, and your roll.
ride: this skill not only includes riding a steed (be it a horse or hippogriff), and whether you fall off when the horse jumps ofer that fallen log, but also controlling and training animals, and any other animal related activity. Calming an animal, taming and training one, or any other animal-related activity (that does not involve killing it) typically uses a ride check.
spells (wizards only): this skill can not be gotten by anyone who is not a wizard. More on wizards and this skill later. In short, you get access to more spells the more points you put into this skill.
stealth: this skill governs how well you can sneak around without arousing suspicion, or simply be not-noticed when you so choose.
swim: how good you are at staying afloat when in the water, or how good you are at getting to land. Too much weight can add negative bonuses to this skill: if you're wearing or carrying more weight than 10x your strength, then you roll a strength check every 10 feet you climb- failure gives you a -1 to your climb check and a +1 to your next strength check. These negative modifiers are additive, and each time you fail the check you add to your negative modifier.
When combat begins, each side rolls an initiative for their team. This uses a 1d20, and whoever rolls higher goes first. Every member of the team that goes first goes, and completes their actions. Then the other team goes, and if their is a third team or fourth team, they continue in that order. A team is a group of people allied to each other; the PCs cannot split into two teams.
To attack someone, the attacker rolls a 1d20. They add to this the fighting skill that applies, and any other bonuses that apply. If the resulting number is greater than the victim's armor class (AC), then they score a hit, and can deal damage. However much damage they deal depends on the weapon. A person's AC is determined by adding their armor/shield bonus to their reflex. For example, a person wearing leather armor (which adds +2 to AC) with reflexes of 12 would have AC 14.
There are three things that can affect how much damage you deal. The first of these is getting a critical hit. When attacking someone, if you roll a 20, without any bonuses added to it, you get a critical hit, which means you strike in such a manner that you deal double damage. You automatically hit with a critical strike. Some weapons get critical strikes on a 19 or a 20, but deal less damage when they do. The second is getting a critical miss. When attacking someone, if you roll a 1, without any bonuses added to it, you get a critical miss, which means you strike in such a manner that you hit either yourself or an ally. Randomly determined who you hit, either by each person rolling a die and whoever is highest gets hit, or using a d(number of players) with each player getting assigned a number, and then you deal half your normal damage (roll normally, halve, and round up). The third way is to deal a glancing blow. If you, after rolling and adding bonuses, exactly equal their AC, then you deal a glancing blow, and deal half damage to them.
For example: Bravius the Brave is a level one fighter, who wears leather armor, has a reflex of 9, 6 points in the fighting (melee) skill, and wields a hatchet (1d4 damage). He specializes in axes. Bravius encounters a ferocious bunny, the sort you'd see in Monty Python and the Holy Grail. He decides to kill it. Now the bunny, though it lacks armor, has reflexes of 17, ten points in the fighting (melee) skill, and a nasty bite that deals 1d10 damage. Bravius is in a little over his head. Bravius and the bunny each roll initiative, with Bravius getting an 18, and the bunny getting a 9, so Bravius goes first. He rolls and tries to hit the bunny, getting a 15, +1 from his fighting (melee) skill, and +1 from Weapon Specialization, getting a 17. Since the bunny has an AC 17, Bravius gets a glancing blow, rolls a 2 for damage, and thus deals one damage. Since Bravius has no buddies, the bunny gets to go. The bunny rolls a 12, adding +2 from its fighting (melee), and since Bravius has AC 11, the bunny hits. It rolls damage, getting a 9, meaning that Bravius (with 13 HP) has 4 hit points left. Bravius valiantly rolls a 15, meaning he misses, and so the bunny goes again. The bunny rolls a 20, meaning that it critically strikes against Bravius. It rolls a 10 for damage, meaning he does 20 damage to Bravius. Since Bravius only had 4 HP left, he dies in a gurgle of blood with his throat ripped out, the bunny victorious.
During character creation, a player rolls a 1d20. If that player rolls a 20, then their character is a wizard, and can thus perform magic. If the player truly wants to become a wizard, but does not roll a 20, then they can spend a Fate Point (explained below) to make their character a wizard. This makes the PC have negative one Fate Points. This is the only time that a player can spend a Fate Point to become a wizard (with the exception of this playing a young character between the ages of 10-18), or have negative Fate Points.
To do magic, a wizard uses mana. Each magic reduces their mana by a set amount, with each magic varying in its mana cost. A first level wizard has 1d6 mana points, with each level increase adding a d6 of mana to that. Every hour, a wizard recuperates 10% of their mana pool (rounding down).
Wizards can cast two types of magics: sorcery or spells. Sorcery is random, and can only be generally "guided." The player chooses how much mana this takes up, which determines the strength of the sorcery, as well as generally what they want to do. The GM then rolls a 1d100 to determine if the sorcery has an adverse affect, or does something the wizard does not want it to do. If the roll is lower than the mana cost, then it is bad for the wizard, and if it is lower than double the mana cost, then it has an additional, unintended effect. For example, a wizard casts a sorcery with the intention of harming a target. The GM determines the affect (since the wizard has a fiery disposition) will be a spear of fire issuing from the wizard's hand. The wizard uses 10 mana to do the sorcery, and the GM rolls a 1d100 and gets 12. Thus, it has an additional affect, which the GM decides will be to make the room completely dark except for any light from aftereffects of the fire spear.
Spell magic typically is less dangerous than sorcery. The worst thing that can happen with a spell is that the wizard loses his concentration and cannot cast it after wasting his mana. Of course, the affects are usually slightly less powerful than sorcery. A spell can be cast as many times as the wizard wants to, as long as he has the mana for it.
For the Atheus system, I shall be using Murometz's wonderful Fate point system. For performing excellent in-character actions, good role-playing, or numerous posts (in short, being a good player), you are awarded Fate points. At any time, a player can spend a Fate Point to re-roll any roll, and uses the better of the two rolls. At specific junctures, which the GM names, the player can spend a Fate Point to level up.