On IRC I realized there's a bit of confusion when it comes to faster-than-light (FTL) travelling, so I'll make a quick summary of the technologies/gameplay mechanics involved in the FTL/HIP travel and how they relate to each other. This will explain why the HIPs need to be in a certain way and not another.
Ships are basically equipped with 3 types of drives ( let's say for simplfying purposes that they're all a 3-in-1 drive ).
- The standard navigation/combat drive provides normal accelerations, typically what you experience in the ICP.
- The impulse/cruise drive provides light-speed and accelerations necessary to reach light speed within a minute.
- Finally, the FTL drive.
The FTL drive is based on hyperspace theory. A wormhole opens and creates a "shortcut" in hyperspace, leading to the destination very quickly. There are two important concepts here:
- the wormhole tunnel, while being a shortcut compared to normal space, has a positive length. It means that it takes time for a ship to travel through it.
- once in hyperspace, your ship goes on its momentum and maintains a constant velocity.
Therefore, the speed at which you'll travel through hyperspace, and therefore the time it takes to reach your destination, is a function of the velocity at which you were going when you entered the wormhole.
Other things of importance:
- when the wormhole is created, you can see a "jump cloud" effect both at the entrance, but also at the destination, which can be analyzed by scanners ( so a pirate can detect where a ship jumped to, or if already in the destination system, where a ship is coming from when it'll arrive ).
- the time it takes to travel through hyperspace is exponential: it might take hours if you're jumping at 0.1% c ( c being the light speed ); minutes at 10% c; maybe 30 seconds at 50%, and maybe 10 seconds at 99% c. Numbers are irrelevant here and will be adjusted in beta.
- when you want to jump FTL, you have to select a destination. The probability to succeed the jump is based on (approximately) the ratio between the mass and the distance to the target. So it'll be easier to target a massive hot blue star than a small brown dwarf.
- jumping to planets will be possible intra-system, or maybe even from neighbooring star systems if the planets are massive enough.
- your destination location in your target star system is roughly in line with the direction formed with the source star system ( your exit point is not random; two ships jumping from the same nearby location and having the same target will end up in the same location in their target, assuming they both succeed the jump of course ).
- failure to jump might cause a lot of effects, ranging from jumping cancelled to drive damaged, to jump on a wrong location, etc..
How it relates to HIPs:
- the HIP needs to have an acceleration structure before the ship reaches the entrance of the wormhole. Of course it might be possible to leave the acceleration structure, but in order for the travel through hyperspace to be fast enough, the ship must be entering the wormhole near light speed. Targetting the entrance of the wormhole when you're going near light speed is next to impossible, and certainly not practical, hence why the acceleration structure is necessary.
- the wormhole is permanent; in other words, it doesn't open or close when a ship wants to pass through the HIP.
- ships will have to request for an authorization before they can pass through the HIP. There will be a tax going to the HIP owner ( initially, the core systems governments/companies ).
- I'm not decided yet whether there should be a decceleration structure at the arrival or not.
- the location of the HIP entrance, and the location of the destination are fixed ( they don't change over time ).
- the HIP should include massive defense stations - those structures should probably be the most well defended things in the whole galaxy.
- the HIP should have an industrial design, but not a garbage/chaotic one. It should be well organized, and probably symmetrical.
- the wormhole/event horizon itself will be spherical, but probably added in engine with a special effect: it's not part of the HIP structure; you should just "reserve" some room for it at the end of the HIP.
- the acceleration structure should probably be a cylindrical structure rather than a ring. This is because when your ship is nearing light speed, it becomes impossible to affect its velocity and make it follow a curved path.