Hyperspace

Hyperspace is a dimension that exists beneath Realspace. Hyperspace is the primary method of faster-than-light travel in The Twins

In hyperspace the laws of physics are different, there is simply no light speed barrier in hyperspace, allowing faster-than-light travel.

Hyperspace is a violent dimension, eddies and currents can throw a ship off course, so the governments of the galaxies created “Hyperspace Routes” or “Hyper-routes” which are charted tunnels of hyperspace, these tunnels always exist, a ship doesn't even need a hyperdrive to travel in a hyper-route, the tunnels are held open at either end by large space stations which send small drones through the tunnel that stabilize it. Hyper-routes are the only hyperspace tunnels that are not in straight lines, they curve as necessary.

Objects in realspace produce gravity-shadows in hyperspace, normally these are not a problem, but the larger the gravity well, the more dangerous its shadow is. Planets and stars must be taken into account when plotting a hyperspace course, as colliding with a gravity shadow usually results in the ship being destroyed. Hyper-routes have an HVR, used in the same way as a ship’s HVR. Most routes leading to either of the galactic cores have an HVR of 8 or more. “Rural” routes tend to have HVRs of 5 or less.