Since the early days of D&D, people have looked at the fat list of magic spells and thought, "Man, I wish I could do X," or "I'd like it better if magic worked like Y instead." In some games, making up new spells (or other powers and effects) is all part of the rules.
- In Buffy the Vampire Slayer roleplaying game, witches and other magic-users expressly create their own spells ahead of time by "researching" them, then building them from the ground up via a checklist.
- GURPS. Exactly how spells and powers are rated and balanced isn't made obvious.
- While Dungeons & Dragons games, post 2nd edition at least, tend to have very thorough options in the core rules, the Dungeon Master's Guide carries extensive information on making new magic and items.
- The first supplement of REIGN includes an exhaustive guide on how to create new magic spells and schools, and encourages players and Game Masters to make their own.
- Ars Magica may be the Trope Maker, or at least Trope Codifier, for freeform magic in games. Spells use pseudo-Latin "power words" to create spell effects on the fly.
- Mage: The Awakening and Mage: The Ascension: If you've got the power and the skill, you can do it.
- FUDGE, admittedly a tool-kit game, includes numerous complete magic systems, most of which are rather loose on their own.
Needs More Examples
- Eternal Darkness has a Rune System. Essentially, all you need are three types of Runes (Spell, Target, Alignment) and you can mix and match them into whatever spell you want to create. Medallions called Circles of Power have a number of slots you can use to mix and match, from 3 to 5 to 7. If you have the right runes you can cast a spell even if it's not on your list, though there are only a certain number of valid combinations.
- Nox allows wizards and conjurers to create custom traps (stationary ones for the former, living summons for the latter) with up to three spell effects that they already know. Once a trap is triggered by a enemy's proximity, all three spells are unleashed at once. On the downside, creating a trap requires enough mana to power all three spells, which is expended at once, without a chance to regenerate—if you don't have that much, you can't create that trap.
- Creating your own spells in The Elder Scrolls is not just an option in multiple games, but it can quickly lead to hilariously unbalancing the game.
, needs a better name.