My brainstorming for what 5E D&D could look like made me think that it would be interesting for the game to have clear but strict rules of magic. For example, sorting spells by variety - power words, chants, trances, rituals, summonings, etc. Each variety of spell would have a predictable physics that people in the world can act on: for example, stuffing cotton in their ears to resist a power word.
I think this kind of system has a lot of things going for it. Durations (as long as your focus continues) and ranges (as far as your voice carries) can be unspoken and unwritten. Non-magicians can meaningfully interact with magicians ('He's just summoned a demon!' 'Quick, grab his hands and make them punch his own face!'). Puzzles and mysteries can be meaningfully solved, because even magic obeys certain understood rules. You can cut off a magician's hands and he still has some options; you can throw a sorceress gagged into a prison cell and she knows exactly what spells she has available to get her out of that mess.
What I've written down doesn't have any game mechanics or actual spells attached. But I think it's a proof of concept for how magic could work in D&D or really any other fantasy RPG, and I'd like to have your thoughts and contributions.
What I have so far:
Focus: Concentration. You can only focus on one thing, at most. You cannot focus on anything if someone has just wedged a bucket onto your head. A keen observer might be able to notice that you are focusing on something; that does not guarantee that they can figure out what you are focusing on.
Voice: Speech, song and other noises made with the mouth open.
Sacrifice: Material components, your own son, goats, hopes and dreams, etc.
Gesture: Unimpeded motion of at least one and ideally two hands and arms.
Maybe you can hum a sub-standard chant. Maybe you can summon a demon with just the gesture of wiggling your fingers. But it won't be easy.
The varieties of spell I've come up with so far are:
Require a single whispered, spoken or shouted magical word that the single target creature can hear. A power word never changes; someone who has heard it several times will recognise it.
Power words do not have a duration. If a power word starts a fire, it burns until it is put out or burns itself out.
Requires focus; requires a continually repeated whispered, spoken or shouted magical word or phrase that every target creature can hear. A chant never changes; someone who has heard it several times will recognise it.
Chants last while the voice and focus are maintained.
Requires continued voice, continued gestures and a sacrifice. It also requires time. It does not require focus.
A three-part process with different requirements.
Requires a gesture and a sacrifice. This summons an entity, which acts according to its own will unless Locked.
Requires focus. This stops an entity from acting according to its own will.
Requires continued gestures and focus. This causes an entity to act according to your will.
Can you come up with more varieties of spell, more components for spells, etc? I'd be interested in seeing what sorts of ways of working magic you can come up with.