Back at University a teacher of mine used to call UNIX scripts spells. I guess that’s pretty much right. A series of unpronouncable words and strange symbols, which actually do something, but often its hard to see what actually happened and the results can be as incomprehensible for the layman than the commands themselves. Sounds like magic to me.
(I’m not even bringing up Clarke’s third law. Except this much.)
On the other hand, if that’s magic, it has a very specific flavor. That kind of magic is very mechanical. To reach your spell, you need to follow certain steps, although there are several paths you can use. Its not a matter of willpower, but rather discipline and creativity. A beginner might take a while to cast a spell, because he doesn’t necessarily know the best way to do it and still needs or would rather have the manual at his side, whereas experienced casters can rattle off spells as fast as they can talk (or type).
In fact, its common knowledge within software engineering community that a good programmer will be able write roughly 30 times more code than a mediocre one and the code he’s able to write is faster and takes up less resources. In this case becoming a powerful mage doesn’t mean you somehow store lots of power. You are just able to use the power you have in a more flexible way and more efficiently.
Another approach is to have people who pray and meditate to ask their gods for favors. This involves mysticism and learning secrets kept even from most worshippers, usually also following rules set by the god or emulating the deeds of the god, or those of saints of the same god from the past. This way they can channel the power of the god.
Third way is to have people, who are innately powerful, but need experience and willpower to use magic. Depending on the situation, finesse might be harder to learn then learning to just blow things up. This is pretty much the way magic is usually depicted in fiction. You just have the talent or you don’t. Then you just need to work to master it, although the main character will often have innate edge as a sort of “chosen one”.
The way this is done in a game will affect much of what the game feels like. Is magic routinelike and commonplace, like in the D&D-family? Or is it like in Mage, where you can learn bunch of different tools and form a spell from them by taking things from here and there. You can choose to take your time if you feel its too risky otherwise.
In D&D when you cast a spell, its pretty much a decision based on how much damage can you do. There’s no pomp and circumstance. Its just another weapon in the arsenal, with different limitations. Nothing more.
In Mage, spells are always a big decision. They involve a risk and require a certain amount of creativity from the player. Although those spells are often less powerful than their D&D counterparts, the way they are handled brings them to the forefront and thus make the magic much more important and powerful in the game.
Granted, this is the point of Mage, but its done pretty well, especially for a game from the nineties. Not much of WoD system holds up today, but this is one of the things that definitely does. Its a good early example of how the system can really serve what you want to do, even though it has its problems. (Ars Magica is earlier and probably even better.)
In my mind, magic system should be designed based on what role you want for it in the game. In HeroQuest (Glorantha, at least), all characters know magic from their god and can use it for pretty much everything. Its everpresent. Its just a normal part of life. Therefore, you can add bonuses from your magic on pretty much everything (depends, on your magic style really, but this is the base). That partly diminishes its impact, since its just so ubiquitous, but on the other hand, every time you use magic, it is accompanied by visuals, which you are encouraged to describe. Not that you can’t do that in D&D, but the emphasis is so different. You’re thinking about the tactical side of things so much more than the story or “special effects” that those grandiose visuals just get lost in the shuffle.
Although I am a fan of Glorantha, I do enjoy the more magic systems which require more creativity in the use by the player. Mage is a great example, as is Ars Magica. This just brings the whole thing so much importance. You find yourself not relying on magic unless its necessary, not at all times, which makes the magic so much more flavorful and resonant to me.
On the other hand, where are the truly great magic systems of the 2000s and 2010s? I guess they are out there. The strides game design has taken have been so great that I doubt this part of the discipline has been lacking, but I just haven’t come across any.