This article concerns the portrayal of magic exclusively within game rules. For the card game, see Magic: The Gathering. For other uses of the term, see Magic.

Some games or game systems can include a set of rules that are used to portray magic in the paranormal sense. These rules simulate the effects that magic would have within the game context, according to how the game designer intended the magic to be portrayed. The rules can also be designed to balance the game play for the players, so as to not give any one participant an unfair advantage.

Typically magic is portrayed by a set of spells, each of which consists of a listing of the game effects and limitations. The game-spells are often grouped into sub-categories by common themes, so as to limit access and to provide context. These spell themes are typically given designations such as Order, College, School, or Domain. They are often characterized by a common effect, such as Fire, Healing, or Protection.

The spells may have a set of prerequisites (termed "components" in Dungeons & Dragons) that must be satisfied during the course of game play before the spell can be activated. The spell listing will also include restrictions on the time, range, and target location, which are listed in the units of measurement employed within the game. Finally the spell description will list the effects upon the game state.

Magic can also be portrayed within a game through the special capabilities of game-based objects, locations, individuals, and even mythological creatures. Each of these will have their own set of rules describing the game effects of their abilities. Usually these rules will be similar in form and function to the rules for portraying spells.

The most likely game type to include rules for magic are in the fantasy genre. However such rules can also be used in the horror and science fiction genres.

Spell systems

Characters within a game that includes rules for magic are commonly able to acquire the use of spells through some process. Usually this will either be a spell that the character has created; a spell gained from a book or other record; another in-game character that is willing to share the knowledge, or from a mysterious in-game source to whom the character has formed an allegiance.

There are several common approaches for balancing and restricting the use of spells within a game system.

• Memorization — The game character must memorize a fixed number of spells from the list of all spells the character knows. This memorization can only occur once in a specified time period, usually a day, or it may require the character to rest for several hours. This is the approach used in Dungeons & Dragons.
• Point-based — The character has a limited number of points (sometimes called mana, or spell points in MUDs) that can be spent to activate spells. Each spell the character knows has a point cost. The points are periodically renewed through some means; usually by the passage of time.
• Skill-based — The character has a skill rating that defines the chance that a spell will be successfully activated. Failure has some type of consequence, such as personal injury or increased fatigue of the in-game character.

There are also some game systems that provide greater flexibility in the use of magic. These include rules for producing spells that are made up as needed, subject to the game rules and limitations. An example of such a system is Ars Magica.

Magical objects

Many game systems include rules for simulating objects that have intrinsic magical properties. The accumulation and use of such objects can be a significant component of games in the fantasy genre, and they serve a balancing role in long-duration games of escalating difficulty. These objects are carefully balanced by the designer, both by restricting how often they can be put into play and by limiting their capabilities.

There are several common techniques for controlling access to objects used within a game.

• Expendable — Objects such as a potion or a spell scroll can typically only be used once before they are expended.
• Charged — Some objects can possess multiple uses, but each use expends one or more charges. Once the charges are expended the object becomes inert, but a character of great power may be able to recharge it. Other items disintigrate when they run out of charges.
• Periodic — An object can have magical powers that can only be used a fixed number of times within a given period. Typically the period used is a day, a week, or a month in game terms.
• Restricted — An object could work only under certain conditions, such as a particular location or when a certain type of target is chosen. It might work for only certain categories of beings, such as characters with specific skills, moral ethos, or a particular in-game race or gender.
• Slot — Many magical objects must be worn or carried. These take up a "slot" on the body that prevents use of other magic objects that require the same slot.
• Faulty — The object might not always work as intended, and it can have unpredictable effects when it malfunctions.
• Skill use — An object can provide a magical benefit that only operates when the owner employs a particular skill successfully.
• Cursed — An object can be cursed, and have a negative impact on the character that acquired it. Typically such objects are disguised as a beneficial item until they are placed into use.

An object can have multiple magical properties, each of which can be limited in a different manner. Thus a magical staff could have a fixed number of charges that can be spent to create a "blinding flash of light"; be able to provide "magical illumination" for several hours each day, and possess a permanent ability to "glow in warning" whenever it comes near a poisonous plant or animal. This staff must be held in both hands for the magic to "work", thus using up the hand "slots". It may also only operate for a character that also knows how to produce certain types of spells.

A few rare magical objects possess an innate "intelligence" and personality, thus becoming a non-player character in the game. This concept is similar in some respects to an intelligent robot in a science fiction game or story, although the entity within the object is usually portrayed as more mystical in nature. The character that wants to employ the object must then interact with the intelligence and find a means to persuade it to cooperate.

Some game systems place a heavy emphasis on giving a magical object a well-developed history and unique characteristics. This is usually done to provide depth to the story being told by the game, and to make the "magic" seem less technological and more mysterious. Another technique for maintaining the mystery is to hide the abilities of the magical object from the characters that find it. The characters must then "identify" the magical abilities, either by putting the object into use or by consulting an expert in magical lore. Some game system also include spells that can be used to identify the abilities.