What you know and how you apply it

Chimera's skill system is based on the Action Roll mechanic, which assigns chances of doing something by the attribute used to do it. Skills (abilities learned through training) are special extensions of character attributes and therefore fall very easily into the Action Roll system. With minimal tweaking, this system is adaptable to just about any RPG (including yours).

Skills & Skill Use

There aren’t a lot of skills in Chimera. In fact, topping out at 15, the list is downright sparse.

This is intentional--the idea is that anything your character can do ultimately maps back to one of these skills. When you want to use a skill, a short list makes it easier to decide which one is appropriate for the action at hand. It also implies that skills are general and lack any real degree of specialisation (and, because of traits (described below) this is actually true).

• Burgle (DEX): Pick locks & pockets, pilfer and conceal small items
• Climb (STR): Scale sloping or vertical surfaces equal to your Movement Rate
• Diplomacy (CHA): Communicate effectively with others to get what you want
• Drive (DEX): Operate land-based vehicles
• Fight (STR): Attack effectively with melee / hand-to-hand weapons
• First Aid (INT): Temporarily reduce the severity of a wound
• Knowledge (INT): Speak authoritatively about a given field or in a foreign language
• Observe (INT): Spot details, detect abnormalities, notice peculiarities
• Pilot (WIL): Operate sea, air, or space vehicles
• Profession (var.): Practice a livable trade
• Repair (INT): Reduce structural damage to a machine, vehicle, or building
• Ride (WIL): Handle a living mount
• Shoot (DEX): Attack effectively with missile / ranged weapons
• Sneak (DEX): Move and hide undetected
• Swim (CON): Swim in liquid / near-liquid medium

When you use a skill, make an Action Roll with its corresponding attribute. If the result equals or exceeds the required target number, the attempt is successful.

The Action Roll system allows for normal and critical success or failure, so skill attempts are not simply "pass/fail." Instead, Normal Success is enough to do the job, Critical Success does the job with some added benefit, and Normal Failure either misses the mark or gets the job done with lackluster results. Critical Failure, true to the precedent set by roleplaying games throughout Time, manifests in terrible ways that invariably screw with your PC's plans. The Chimera Core Rules provides guidelines for interpreting results, but ultimately, GMs should apply whatever makes sense in a given situation.

When a character improves a skill, he earns a cumulative Skill Bonus (SB) of +1, which is then added to Action Rolls made with that skill. On the other end of the spectrum, characters can use skills they don't possess, though they can't apply any attribute to the attempt, so the base Difficulty is automatically Strenuous (Target Number 20, if you use Chimera's Action Roll system). Learning the skill later "unlocks" it so the TN reverts to that of the appropriate attribute.

Traits

A character’s qualities and non-skill abilities are known as traits, which can represent any special advantages or disadvantages possessed (I'm told these are not dissimilar to D&D  feats, but, having no experience beyond 2nd Edition, I can't say with certainty).

Traits can augment a character's attributes and skills, and most traits operate automatically, either by adjusting Action Rolls or tweaking game mechanics in the right circumstances. Used this way, traits apply a level of specialisation to skills, allowing you to use your skills in ways others cannot.

For example, the Observe skill helps a character note details in his surroundings. The Track trait builds on Observe when pursuing quarry (and this isn't just tacking a bonus onto the Observe roll); Detect Danger is a trait that lets you use Observe in a new way, specifically to sense bad things before they crush your AT-ST with tree trunks swung from ropes.

Most other traits work in similar ways. The First Aid skill provides temporary medical relief, but the Heal trait makes treatments more effective, and permanent. Disarm lets you use the Burgle skill to nullify traps and alarms. The Diplomacy skill represents effective communications; traits like Bluff, Savvy, Seduce, Persuade, Intimidate, Haggle, Oratory, and Taunt suggest specialised means of getting what you want.

The goal is to provide a lot of flexibility, for players running characters and GMs running campaigns. Because a trait can represent any ability, characteristic, or quality you want or need in your setting, applying (or inventing) them lets you push the rules in any direction you want, without breaking the system.

Final Words

A short, static roster of skills forms a solid and intuitive foundation of character abilities, while traits provide a mechanism for specialising those skills to whatever degree the players and GM wish. The benefits include not touching (or breaking) your game's core mechanics, but also maintaining game balance: anyone (including the untrained) can attempt a skill, but only those with the right traits can perfect its use in the right situation.