Half-Stat Defaults for Spells Douglas

[Regulus_Outrider]

As the Title implies, I'm trying to apply Douglas Coles rules for using Half Stat as the base for skills (Pyramid 3/65) to the Spell system (standard GURPS Magic).

I'm having difficulty figuring out how the skill level for spells is calculated exactly. It seems to be a separate formula from other skills, otherwise the Half-Stat file that already exists would work as is.

What am I missing here?

[Stormcrow]

The Half-Stat file only converts the skill types of skills, not spells. In the file, each skill is redefined, one by one, to use the new Half-Stat skill types. The file doesn't work for spells because it doesn't redefine spell skill types one by one.

To get it to work for spells, you'd have to redefine all the spells, too.

Unfortunately, this redefinition seems to be very non-trivial. I don't know the Half-Stat system — I've got the article in front of me but haven't read it — but here's an example of what needs to be done.

Here's the Accounting skill as defined in the Basic Set data file:

Accounting, IQ/H, default(IQ - 6, SK:Finance - 4, "SK:Mathematics (Statistics)" - 5, SK:Merchant - 5), page(B174), cat(_General, Business)

And here's how the Half-Stat data file redefines it:

#ReplaceTags in "SK:Accounting" with {type(IQ/H[-1]), default(IQ + me::defmod, SK:Finance - 4, "SK:Mathematics (Statistics)" - 5, SK:Merchant - 5), defmod(-@int(0.5 + ST:IQ/2)+@MIN(@INT(ST:IQ/2),@MAX(0,ST:IQ-ST:RuleOf::score))-1)}

You've got to set the new type() and the new default(), and the default includes a complicated calculation called defmod(). And you've got to do this for every spell.

I don't know if that formula varies. If it doesn't, you might be able to add that type() and defmod() to any spell you take, then add "IQ + me::defmod" to the default() for the spell.

[Regulus_Outrider]

Admittedly I was hoping for an easy way to do it. Using a #ReplaceTags with the All option for example, but it looks like I'm going to have to do it separately for each spell. Yuck.

[ericbsmith]

I'd have to go back and look at how I set up the file, but I guarantee I used a spreadsheet to generate that code because, as I recall, the exact formula in defmod() did vary from skill to skill, but it varied by a consistent amount that was calculable (IIRC it was based on the default level from an attribute).
I don't know how half-stat was supposed to work with spells, but likely it did something similar.

[ericbsmith]

And taking a couple minutes to look at the article, if I understand it correctly:
The "effective default" for a skill without a default is attribute/2, at an extra -1 for Hard and Very Hard skills. This means that the effective default for a spell is (attribute/2)-1; if IQ is 10 then default is (10/2)-1 = 5-1 = 4. 1 point in a Hard skill (spell) buys that up to default+4, or 8.

This is exactly the same as having a base level of 5+(IQ/2) as the base attribute value. IQ 10 gives a base attribute of 10, and 1 point in a hard skill (spell) buys attribute-2, or 8.

In either case, it takes buying two levels of IQ to raise that skill by +1.

So unless I'm mistaken, both systems give the same results for skills without defaults (which is all spells), and one of the Variant data files already has 5+(10÷2) as an option:
Variant Magic 4e - Alt Attribute 5 + (IQ ÷ 2).gdf

[Regulus_Outrider]

Thank you, that does the trick.
Can't believe I missed that. I guess the sheer number of available Data Files makes it easy to miss some things.

[DouglasCole]

Originally Posted by ericbsmith

And taking a couple minutes to look at the article, if I understand it correctly:
The "effective default" for a skill without a default is attribute/2, at an extra -1 for Hard and Very Hard skills. This means that the effective default for a spell is (attribute/2)-1; if IQ is 10 then default is (10/2)-1 = 5-1 = 4. 1 point in a Hard skill (spell) buys that up to default+4, or 8.

This is exactly the same as having a base level of 5+(IQ/2) as the base attribute value. IQ 10 gives a base attribute of 10, and 1 point in a hard skill (spell) buys attribute-2, or 8.

In either case, it takes buying two levels of IQ to raise that skill by +1.

This is more or less how I calculated everything. Start so at attribute = 10 nothing/very little changes ("Thou shalt not nerf existing characters") and make it so half-stat applies away from that center.