Advantage Based Magic In GCA

[joshualevy]

I'm trying to write the GDF for a custom magic system.

The basic idea is that no existing stats would be used (no IQ or Will). There are four areas of magic, and each one is based on a different advantage. These advantages would have levels from 3-18, so they would be used much like stats. Each spell would be built off the underlying advantage for it's area of magic.

Currently, I'm planning to implement this in a GDF file as described above. So one of the "areas" of magic might be casting, and look like this (but with a lot more spells, of course):
[SKILLTYPES]
cast/A, cost(1/2/3), base(0), defaultstat(AD:Knows Casting), relname(def), subzero(yes)
[ADVANTAGES]
Knows Casting, 1/2/3/4/5/6/7/8/9/10/13/16/19/25/30/35/40/50, downto(3), upto(22), page(MAI22), description(Allows the character to cast spells)
[SPELLS]
Healing Cast, type(cast/A), needs("AD:Knows Casting"), default("AD:Knows Casting::level")

My goal is that it cost anywhere from 5 to 40 points to be able to use one area of magic, but then spells would be cheap: only a point or four.

However, I'm not expert in GDF files, nor in GURPS magic, so I'd like other people's opinions on how best to implement this. I want it to be easy to use, easy to explain to GURPS players, and easy to implement in GCA.

The big difference between this magic and other magic systems that I've seen, is that no existing stat is involved.

I thought about creating four new stats, one for each magical area (instead of the advantages used above). But I did not go in that direction because I view magic in this world as a combination of being taught and having an innate ability, and that combination felt more like an advantage to me.

I also thought about having more conventional advantages with four levels (rather than the 3-18 above), and then somehow mapping level 1 to be a base 8 for casting spells, and a level 2 would be a base 11, etc. In some ways that feels like it would be easier for players to understand but harder to implement in GCA.

Is there an already existing magic system which does what I want and has a GDF file? That would be great.

Any thoughts on any of this?

Joshua Levy

[Armin]

I think the way you are doing it there probably works fine, and should be easy to understand and work with. I agree that it's probably the simplest way to accomplish what you're talking about.

Now, for the alternative that you mentioned, using 4 levels of advantages....

For that, I would suggest actually using the four attributes as the base for your spells. However, you could continue to use advantages to increase the level of those attributes, so players would never have to deal with the attributes directly.

Give the attributes a base value (maybe basevalue(5) ). Then have the advantages increase that using gives() bonuses with variable bonuses based on level (such as gives(=+me::level*3 to ST:Casting) ).

I think that combo would be cleanest for such a system.

Your spells could still use the advantage in needs() to ensure they have that, but your default would change to be based off of the attribute.