Determining the range of spells

Question

The Basic Set (p. B247) has the following entry for a Fireball.

Lets the caster throw a ball of fire from his hand. This has 1/2D 25, Max 50, Acc 1. When it strikes something, it vanishes in a puff of flame. This spell is likely to ignite flammable targets.

Cost: Any amount up to your Magery level per second, for three seconds. The fireball does 1d burning damage per energy point.

Time to cast: 1 to 3 seconds.

Prerequisites: Magery 1, Create Fire, and Shape Fire.

I am trying to figure out what the range of this spell is?

I am new to GURPS, and have been only skimming the rules for a couple of days, so there is a chance I have just missed some obvious entry about this.

Answer 1

The line you're looking for is here:

This has 1/2D 25, Max 50, Acc 1.

This describes how you aim the spell.

The "1/2D" stat is the number of yards that you can shoot the spell at before it does half damage. In this case, the Fireball does full damage if you shoot a target within 25 yards.

The "Max" number is the maximum range of the spell. If you shoot it at a range in between the 1/2D and the Max, the spell does half damage. In this case, the Fireball has a max range of 50 yards, and does half damage when targeted between 26 and 50 yards.

The "Acc" number is the bonus you get when aiming the spell. If you take an Aim action before firing the spell, you get this bonus to your attack roll.

If you look at the Equipment section on B268 (the "B" there means it's in the Basic Set books, Characters or Campaigns), this stuff is explained. There is also a detailed description of how ranged combat works on B372.

You might also want to look at the rules for Missile Spells, on B240.

Answer 2

You've missed the section of the rules on weapons and ranges. One of the places you can get a primer on range is in the GURPS Basic Set Equipment chapter, page 268. The Combat chapter goes into more detail on page 372. (For an exhaustive list of places in the rules that cover range and things that are relevant to range, see the Ranged attacks entry in the Index.)

What that specific range means is that your target must be within 50 yards to hit them at all, and if they're farther than 25 yards away then they will take half damage if you do hit them. "Acc" tells you the number that's relevant to calculating the bonus to your attack roll granted by taking the Aim action (p. 364).