Most RPGs, both the pen and paper and video game varieties, include the idea of skills. Although they go by various names in different systems, skills are areas of expertise or knowledge in which characters can gain ranks or ratings. A character’s rank is taken into account when resolving actions related to that skill. For example, a lockpick skill measures a character’s ability to crack safes and open doors, while a swimming skill covers long distance swims, trending water for long period of times, and holding one’s breath.
Depending on the game system, the number and type of skills available varies from ten to twelve high-level proficiencies to hundreds of detailed areas covering nearly every imaginable scenario. Game systems striving for universality and encouraging multiple types of gameplay tend towards larger lists while more focused games often support shorter, more targeted specialties. Although part of the game’s mechanics, the skills made accessible to the players strongly communicates the atmosphere of the campaign.
What sort of game is suggested by a skill list that includes occult, library research, archaeology, and astronomy? Does it sound like a game where the characters can expect to encounter eldritch horrors from beyond time and space? What about survival, barter, jury-rig, and energy weapons? Perhaps a futuristic post-apocalyptic wasteland? A campaign relying on intimidate, stealth, streetwise, and thievery is very different than one focused on history, heraldry, warfare, and diplomacy.
The potential list of skills is practically infinite. Rather than strive for completeness a focused list of ten to twenty skills is sufficient to enable a wide range of gameplay if choosen carefully.
1. Decide on the atmosphere and setting of the campaign
A game designer or DM should develop a skill list that corresponds to the play style they want to encourage and that supports the campaign atmosphere they are trying to establish. Is it a swashbuckling and piracy adventure? Dungeon-crawling? Gothic horror? Van Helsing has a very different skill set than Conan but both are appropriate to their worlds.
2. Decide on the challenges the characters will face
A characters’ skills define the possible solutions they can bring to bear on a situation. If the characters will often have the opportunity to talk themselves out of sticky situations rather than fight, you should offer skills like intimidate, barter, and bribery. Likewise, there should be no pointless skills. Every skill should be a Chekhov’s gun.
3. Decide when to be specific and when to be general
The Dewey Decimal Classification reserves the 200s for religion. 220-290 catalogs various aspects of Christianity; 290-300 is reserved for all others religions. Obviously this is culturally imbalanced but it accurately reflects the Western libraries of the 1800s. One should consider specificity and generality carefully. For a super hero-themed game, a science skill may cover every science imaginable–high-energy physics, biology, astronomy–to match the super-scientists common in comic books. A sci-fi themed exploration game may divide those sciences into different specialties: engineering, medical, and xenobiology.