Mechanic Design: Character Skills

Depending on how you play, skills can be a large part of your game. In some cases, they are seperated into combat skills and non-combat skills. In other cases, they are entirely different systems. When designing a skill system for an RPG, it is important to remember that you have many choices to make.

Listed Skills versus Player-Made Skills
One choice you need to make is whether to have a list of skills at all. You don't need a giant list of skills to have a skill system. Players can create their own skills during character creation, and perhaps even during character advancement. The main benefit of a list of skills is that the game can be played sooner and generally with less effort than a game where the players have to make their own skills. In addition, a list of skills can ensure that your setting is reinforced and that roles or niches are filled. It is difficult to say what the main benefit of skills made by the player is, but I believe it has to do with flags. Players make the skills for the action they want to see in the game, so they are directly involved in choosing the content of the game (as long as the GM follows through). Some downsides to a list of skills are that it can be difficult to modify and content may be created from the skill list that players do not want to play. Some downsides of player-made skills are the chance that an area of content won't be covered by a character's skill and some skills will be more powerful than others.

Described versus Undescribed
Another choice you have to make is the level of detail to describe your skills. This is mainly for RPGs with a list of skills, but might apply to player-created skills. Descriptions aren't required at all. The main benefit of having detailed descriptions is the ability to settle disputes with the book rather than negotiating with players. Having descriptions really lets the players know what they can expect to do with certain skills and gives the GM a better idea of what things are taking place in the setting. On the flipside, leaving a skill descriptionless will allow them to be flexible, and should open up the imagination of the players and GM. This may cause some skills to overlap.

Broad versus Narrow
Yet another choice is how broad or narrow of an action do you want your skills to cover. Again, this is mainly for described skills, but might have an effect on the naming of undescribed skills. Broad skills generally means that you will need a smaller list, because each skill covers more area. It also could mean, for example, that anyone good at moving quietly can also hide in shadows well. Narrow skills generally means that you will need a bigger list, because each skill covers less area. List size can have a large effect on how mechanically balanced your list is. Narrow skills work better if you need to create highly specialized character concepts. Broad skills work better if you just need to fill roles or niches with groups of abilities.

One important thing to keep in mind during this whole process is "What problems do my skills actually solve?" The situation that a skill resolves and the situations you expect to arise in play should be the same. One famous example of this not being the case is 3.X diplomacy. The skill is setup to decide whether or not you can convince an NPC to change his disposition towards you, but gives little in actual detail of what gets accomplished. In effect, the PCs are asking "Do we convince the King to let us into the vault?" and the skill is saying "The King is now friendly towards your group". In the end, it comes back to the GM to decide. I believe the skill needs to be re-designed with the situation it wants to solve directly in mind. That may be the case with 4e, anyhow.