Three-dimensional movement

[Coinage]

Hey, quick question. Are there rules for three-dimensional movement in GURPS? I was thinking about something like flying, or combat in space. Any help is appreciated.

[Phil Masters]

Transhuman Space: Martial Arts 2100 has some basic stuff on zero-G combat...

[Stormcrow]

The basic trait to have is the Flight advantage. There are several forms listed. Take Aerobatics skill for greater control and Flight skill for more endurance. Basic movement rules are on page B354. See the special rules for flying combat on page B398.

In freefall, always use the lower of your DX-based skill or your Free Fall skill. 3D Spatial Sense advantage gives a +2 bonus to Free Fall. If you're wearing a spacesuit, always use the lower of your DX-based skill or your Vacc Suit skill.

If you're battling in spaceships, get GURPS Spaceships for an abstract space-combat system.

[Coinage]

I was thinking of using Mass Combat rules with flight for a large space battle. How does it run in game? Is it pretty smooth? Or is it clunky?

[Rolando]

You may be better by looking at the Spaceship line. There are rules exactly for space battles, big and small.

But, you can make it work by abstracting things, depending on how your space combat work you can make ships conform to land elements (destroyers are tanks, missile or torpedo boats are artillery, etc) and use the Mass Combat rules.

Rules are abstract enough, description is all that matters, and internal consistency of course.

[Coinage]

Right. So, if I use the Spaceship line with the Flight rules, then I should be able to simulate something like 3D, right?

Basically, I am hoping for something a bit like the Homeworld video game series. Not a complete match, obviously. I was thinking about adapting Ancient Greek naval warfare in space. I found some interesting rules here: https://www.gameinthebrain.com/2014/...naval.html?m=1. I was thinking of adapting those rules for 3D combat.

[Rolando]

I just remembered that Mass Combat includes naval elements :/

the Renegade Legion line (from FASA) used mostly naval warfare concepts for their Leviathan game, with broadsides and slow ballet like maneuvering.

But the GURPS Spaceships 1 and 3 (maybe also 4 for extra detail) will have everything you need to recreate the Homeworld feeling of space combat. The 3D-mensionality of space is abstracted but it is very important for the descriptions.

[Coinage]

Okay, GURPS Spaceships 1 and 3, and 4. There is still 3-D movement there, right?

[Rolando]

not really, it is 2d but as spaceships are 3 part sticks they have a 120 degrees arc in the front and the back, 60 degrees to each side for the center part. So, by making those arcs a cone instead of a triangle you can emulate 3D easily by treating "altitude" with a counter and having some graph paper to check for arc of fire and intervening objects at different altitudes.

The tactical space combat is also vector combat, I remember Home World wasn't inertia nor vector, it was more like WWII in space, so maybe you will have to adapt all the delta V and other physics to make it simpler. Probably just ignoring them for anything but relative speed.

Still, I think it will give you a great starting point.

you can always make things very abstract and cinematic with the use of the Basic books and maybe using Mass Combat for the big picture and logistic stuff.

[Coinage]

Okay, so I would basically have to extrapolate from GURPS Spaceship and expand it to include 3d movement. And for fleet movements, I would use Mass Combat movement, and then apply the "Flight" advantage to all the units, allowing for a 3d movement in space.