Traveller

Traveller is a science fiction game setting which was first published in the 1970s, and which has since gone on to be one of the longest running and most popular SF games.

The Yags SF rules are currently being used to run a campaign set in the GURPS Traveller setting. This is set at the end of the Classic period and ignores the collapse of the Imperium caused by the assassination of the Emperor.

Yags SF assumes a Traveller-like campaign, partly because this is the setting it has been used to run, and also because it makes sense. Traveller uses the view of science fiction from the 1970s, and doesn't get sidetracked by the revolution in computer and genetics technology that came after. The setting is nothing like the future will be, but this allows the GM and players to concentrate on human characters in a human society, rather than playing minds uploaded in AI generated virtual landscapes.

Space Combat

One thing about Traveller is that it assumes combat in space takes place across millions of kilometres, with beam weapons being effective across these scales. Yags SF assumes a smaller scale for spaceship combat, one which is more action orientated (but not as action and SFX focused as Star Wars for example).

By limiting combat to a few hundred kilometres, it makes smuggling operations and blasting your way out of starports that much easier - a single patrol cruiser can no longer pick you off from high orbit as you attempt to escape to make a Jump to hyperspace. Fighters, though still limited in role, are also easier to imagine when they are fighting combat at ranges of kilometres rather than thousands of kilometres, with turns measured in seconds rather than hours.

If you've played a computer game like Eve-Online, then you'll have an idea of the sort of scales that Yags SF assumes. In all, it is thought that the shorter ranges provide a more player-friendly environment, and may actually be more realistic. Focusing lasers over very long ranges is actually very hard (if you thought laser beams didn't spread out over distance, think again), especially if you want it focused enough to cut through ship hulls.

Anti-Gravity

Another assumption made by Yags SF, which is a departure from Traveller, is that grav technology doesn't allow anyone to fly up into orbit on a supermarket trolley. In some respects it is closer to the repulser technology of Star Wars - grav vehicles have an operating ceiling above which they can't go.

The main reason for this is that without this limitation, there is no such thing as ground vehicles. Tanks, civilian cars and hover boards become space ships, which is a blurring that removes specialisation.

It is assumed that there are two types of 'grav' technology - thrusters which are used by spacecraft, which are big and expensive but which can provide thrust in space; and repulsors which are more like reverse tractor beams, pushing against nearby matter to provide lift. The ability of a repulsor to provide lift drops off rapidly with distance (to a very high power), so many vehicles are limited to a few tens of metres altitude. Repulsor tech is relatively cheap however, so is used in vehicles designed for use within an atmosphere (high-altitude repulsors, limited to a few tens of kilometres are available for aircraft at high tech levels).