This is the start of a multi-blog series on the basic and secondary attributes in GURPS. If you're new to the system, what are some things you'll want to think about? GURPS is point buy, so it's not the dice but you that decides what level your stats are. Today we tackle DX and two stats derived from it (at least partly) - Speed, which is figured equally from DX and HT, and Basic Move, which is figured straight from Speed.
For other looks at DX, Basic Speed, and Move, check out:
Ravens 'n' Pennies
For more in this series, please Gaming Ballistic's GURPS 101 page.
How much DX do I need?
The more, the better. Generally, for combatants, DX will be one of your highest stats, if not your highest. Skill trumps just about everything else in importance in GURPS combat, and DX is what you base most of your combat-related skills on.
From a pure min-maxing perspective, you're going to want at most 4 physical skills that you improve past 4 points invested; beyond that you're better off increasing DX. DX is the "physical skills generalist" ability. The more DX you have, the better you are at dozens of physical skills and all combat skills (ranged, melee, and unarmed). A specialist - someone who dumped the points you put in DX into one or two skills related to a specialty - will kick your ass in that specialty but you'll be better off over a broader area of ability.
When you're designing your guy, keep that in mind - DX is a good way to get broadly good at physical skills, but you're still going to need to focus on the specific skills you need to succeed.
DX also does a few other things:
0.25 Points of Basic Speed - Every point in DX gives you +0.25 Basic Speed. See Speed for why this matters.
DX Rolls - There are a lot of non-obvious DX rolls built into GURPS, very often to not fall down. DX roll not to fall after a kick. DX roll to not fall when slipping. DX roll to not fall after knockback. But that's not all - over on RPG Snob Jason Packer has a possibly exhaustive list of DX rolls in GURPS.
DX & Defaults - A high DX helps a lot when you do something new, because you get a favorable default. A trained person will usually be better unless your DX is obscenely high or the task is extremely easy. But a good DX will let you get pretty far. A character with a DX of 15 (pretty damn high) can try any physical skill that can be defaulted at between a base 9 (for DX/Hard skills) to 11 (for DX/Easy skills); compare that to a trained DX 10 person with 2 points in any of those skills (9-11).
As I mentioned above, specialized skill matters, but DX lets you try a lot of stuff with a reasonable chance of success. Think Michael Jordan playing baseball - he just couldn't excel. DX + lots of points in skill beats DX + few points in skill, but high DX meant MJ could still make a go of it . . . I couldn't hit .200 in AA ball. In GURPS, that could be because he'd get a superior DX.
How Much Speed Do I Need?
As much as possible, as usual, but most people just stick with what DX and HT provide for them. It's not cheap (20/level, the same as DX and double that of HT) and you tend to get a pretty good score if you get a reasonable DX and HT (12 in each will give you Speed 6, a solid score). Plus, since it's not a double dip like DX and HT (which do a lot besides increase your Speed) you can usually find something else to spend your points on. Still, it's a good thing to have.
Speed - Encumbrance Level = Dodge - Dodge is the best damn defense in GURPS. Let me just repeat that. Dodge is the best damn defense in GURPS. It works against just about everything - some attacks cannot be Parried, others neither Parried nor Blocked, but few can be Parried or Blocked but not Dodged. It also, barring optional rules, doesn't get reduced for multiple uses in one turn.
And Speed is your basic Dodge score. Dodge is so good that Enhanced Dodge costs 15/level and all it does is raise Dodge; Speed is 20/level and also helps you move faster.
Initiative - Initiative in GURPS is fixed-order; once set, it stays that way. If you use Speed-based initiative (not like my lazy round-the-table initiative) your Speed (including fractions) helps determine when you go. Since GURPS resolves effects immediately and vigorously supports death spirals (the worse off you are, the more likely you are to keep getting worse off), going first is a nice little edge.
Fractional Speed - Just remember you can buy up fractional Speed. So if you have DX 14, HT 12, and Speed 6.5, you can spend 10 points and get Speed 7. This is especially tempting if you're 0.25 off from a full level, since Speed's effects on Dodge and Move drop all fractions.
I could spend a whole day talking about Move, which I think is gravely underrated, especially in internet featureless plain fights to demonstrate the superiority of one style over another. In actual play, Move has determined what people do this turn (or the next one, or many in a row) more than almost any other single stat or score.
Basic Move is equal to your Speed. It is sometimes modified by traits like Gigantism, which gives +1 Basic Move, or by direct purchase of Basic Move at 5/level.
In a "normal" game, you usually want a Move score between 5 and 7; 8+ is great but it's not critical to have. Below Move 5 and you're starting to be kind of a slug on the battlefield. Below Move 4 and you're a slug. Move 2 or 1 and you're limping along hoping the fight comes to you.
Move and Encumbrance - Move is also influenced by Encumbrance, based on a multiplier (so No Encumbrance is x1, Light is x0.8, and so on). This is where ST matters a lot, because a moderately-fast but strong guy can load up and stay moderately-fast, but a weak but speedy guy needs to keep unencumbered to stay fast. Your ST plays a role here, too, because your BL determines how much you can carry without dropping down in move. I've seen players spend time number-crunching to determine if +1 Move or +1 ST (potentially just +1 Lifting ST) was the better way to ensure they could add more gear and stay at Move 4+ (5+ if at all possible).
Move and Slam - Slam damage is figured off HP multiplied by Move, so every point of Move you have is 1 more full multiple of HP you get to leverage in the slam. Even a very high HP character cannot do much without a solid move score.
Half Move - Half Move is how much ground you can cover on an All-Out Attack and you move at half Move when badly injured. When doing All-Out Defense (Increased Dodge) you get to move at half of your Move score. It's worth keeping in mind these when designing a character who'll want to cover ground on all-out assaults or shimmy to cover more easily when All-Out Defending.
All Move really does is help you cover ground, but one a tactical map being able to cover a lot of ground lets you be the one to decide where to fight, where to go, and who to deal with and who to avoid. It's simply that, but that's a very big thing indeed.