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PDF versions of YAGS can be downloaded for free from the links below. See Downloads for the full list of rules.


YAGS is released under the GNU Public License, and as such the full set of source documentation is available, as well as the final PDFs above.

YAGS Source

All content on this site is copyright Samuel Penn, © 2013. All textual content is licensed under the GPL version 2. Original photographs may be considered public domain.

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Space Weapons

Since YAGS SciFi aims to emulate the softer side of science fiction, the focus is on providing a range of different energy weapons at technology progresses, without too much regard to the scientific and practical validity of such weapons.

One game design requirement is to keep combat in the range of 10km - 1000km. This may be soft science fiction, but it isn't Hollywood, so space combat occurs at ranges where most targets are points of light, but not at such great distances that planets are points of light. The limit on range is so that small (player character owned) space craft can blast their way out of a space port and have some change leaving orbit without being shot down. Once combat ranges reach 10's of thousands of kilometres, a single patrol ship in orbit becomes unavoidable unless you can keep the planet between you and it.

Weapon Mounts

Light Turret

Mass: 1dt
Size: 10

The basic light weapon mount, common on civilian ships as point defence and anti-pirate action. Used as anti-fighter and anti-missile point defence by capital ships.

Heavy Turret

Mass: 3dt
Size: 15

The heaviest type of mount generally found on civilian vessels, but a typical 'light' weapon by mid-sized military vessels.


Mass: 10dt
Size: 20

Generally only found on military vessels, the largest of the turreted weapon mounts. Big enough for use in ship to ship combat, with more flexibility than bay mounted weapons. Considered too slow and ungainly for use in point defence.

Small Bay

Mass: 50dt
Size: 25

The smallest 'main weapon' for larger military vessels. Tends to be limited to energy weapons or missile arrays.

Large Bay

Mass: 250dt
Size: 30

The largest non-spinal weapon mount.

Technology Levels

TL 7

This is the late 20th century, so weapons are pretty much limited to missiles and slug throwers. Ranges are in the 'few kilometres' region mostly due to aiming limitations.

Chainguns: The simplest weapons for space combat. At this technology level, the only practical way to hit targets at such long ranges is to fire a lot of bullets at the target. Tend to be used through to TL 9.

Nuclear missiles: Good range, but limited delta-v at low technology levels. Very destructive if they get close enough until the invention of nuclear dampers.

TL 8

TL 7 weapons are still common at TL 8, but new technologies are beginning to become available. At this stage they are still experimental, though could probably evolve faster if there was greater need than there has been in 'the real world'.

Railguns: Similar to chainguns, but using electromagnetic propulsion to fire a small number of rounds at very high velocity. More accurate, longer ranged, but still limited relative to higher tech alternatives.

Massdrivers: The same technology as Railguns, but designed to fire a single high mass kinetic round rather than multiple small ones. Has a higher destructive ability, but very inaccurate against small targets.

Lasers: At TL 8 lasers are possible, but not that effective. They tend to do limited damage but have the advantage of high accuracy at longer ranges than railguns.

TL 9

Lasers become the primary weapon of choice at this TL, though they are still expensive so railguns and massdrivers are still in heavy use.

Nuclear Cannon: Directed energy weapon, detonate a small nuke and direct it at the target. Incredible amounts of damage, but very limited range.

Sandcasters: Used for defensive purposes. They deploy fine dust particles which absorb and reflect light, used as a defence against lasers, and to some extent, particle beams (which haven't been invented yet).

Massdrivers: These are large, spinal mounted railguns. They cause massive damage at long range, and have greater accuracy than railguns due to their high speed, but a ship needs to be built around them. The difference between a railgun and a massdriver is really one of implementation rather than technology.

Plasma Drives: Reaction drives can of course be used as weapons, but they are diffuse and difficult to focus. As such they have short ranges and aren't considered practical.

TL 10

Particle beams: Particle beams are more damaging than lasers, though aren't quite as long ranged.

Nuclear pumped x-ray lasers: Nuclear missiles which power a highly destructive x-ray laser at the target. Greater effective range than a standard nuclear missile, and harder to target.

TL 11

Plasma cannons: Fire bolts of super heated plasma. Shorter range than lasers or particle beams, but more damage. Due to their explosive effects, tend to be good against larger targets.

TL 12

Meson guns: Make use of weird stuff to avoid armour. Tend to be only used as spinal mount weapons until much later tech levels.

Xasers: X-ray lasers. Better range characteristics than standard lasers, and these ones don't need to have a nuclear bomb behind them.

Nuclear dampers: The ability to prevent nuclear explosions in close proximity.

TL 13

Anti-matter particle beams: Highly destructive, dirty weapons. Have to use low density beams for safety reasons, so not as bad as they might sound, but better than standard particle beams.

TL 14

Fusion cannons: Hotter, more deadly versions of plasma cannons, heating the bolts up to fusion temperatures before firing.

Gravity pulse gun: Uses a mix of repulsor/tractor technology to shake the target apart. Ignores armour, but very short range.

TL 15

Grasers: Gamma ray lasers.

TL 16

Plasma beams: Beam version of plasma cannon.

TL 17

Fusion beams: Beam version of fusion cannon.

genres/scifi/tech/space_weapons.txt · Last modified: 2018/08/30 20:48 by sam