Let's talk about...
There are many ways to imagine FTL, but the one chosen for the game will help in many ways to define its feel. Here are some options from fiction and games:
Alcubierre Warp Drive (Star Trek): Creates a "bubble" of spacetime that is warped in such a way that it moves, carrying whatever is inside along with it; while matter cannot exceed the speed of light in space, warped space can do so. While the fictional drives have an honestly peculiar look to them, science suggests that a real drive of this type might involve two large rings, one after the other, which create and maintain the bubble of warped spacetime. Ships can apparently overtake other ships, and combat in warp drive is evidently possible.
Hyperdrive (Star Wars): Honestly, I'm not sure how this is supposed to work; the special effects from the movies suggest it works like the Alcubierre drive, but "hyperdrives" should move ships through "hyperspace" i.e. 4 (or more) dimensional spaces. Ships in hyperdrive cannot be tracked or intercepted, so no combat can take place while in FTL travel.
Stargates (Stargate SG-1 and later series; Buck Rogers in the 24th Century series): In this type of system, ships don't move faster than light; rather, a device called a stargate creates some form of folded space or wormhole connecting two distant points. Generally, the exit point is also a stargate. Some versions of this system require a receiving gate, and gates must be distributed via normal-space (sublight) means. This slows humanity's expansion into the galaxy, obviously. Since travel is effectively instant, there is no combat effect.
Hyperspace (Babylon 5): In this system, ships travel through a parallel dimension of some sort, where traveling a relatively short distance results in moving a substantially longer distance in normal space. Smaller ships may not have the ability to open gateways ("jump points") into or out of this space, but may still be able to use it by entering and exiting jump points created by larger ships or by a kind of stargate-like device. Combat in hyperspace may or may not follow the same rules as normal-space combat, but is evidently possible.
Jump Drive (new Battlestar Galactica): The ship folds space, teleporting instantly from one point in the universe to another. There is a distance limit per jump, called the red line. "Spooling up" the jump drive takes some time and substantial power, and jump calculations also take time.
Quantum Drive, aka Stutterwarp (from a game I can't name due to the OGL): The drive creates a field that causes the elementary particles of the ship's matter to tunnel repeatedly, in the quantum sense, moving together in lockstep at a very high frequency. To an outside observer the ship remains visible in normal space, but begins to move faster than light; to an inside observer, it doesn't seem to be moving at all (there is no feeling of inertia or acceleration), at least until you look outside the window. Combat in stutterwarp is basically impossible because the ships are moving faster than their own light, far too fast to detect each other, except possibly in a pursuit situation (but a single bobble of a fraction of a second's duration will separate them by much too far to recover).
Wormhole Drive (Star*Quest game, Space Force game): This one is my own invention. The ship creates a wormhole and enters it, exiting the far end several light years away. The wormhole's interval is partly timelike, such that for normal characters (who exist in three spacial dimensions and one time dimension) the far end does not yet exist when the near end closes. Thus, the ship is carried along in a pocket of spacetime from the near end to the far end. Ships cannot intercept each other, and combat while traveling is effectively impossible. Sometimes described as being carried along by a collapsing wormhole, which is more or less accurate.
As an aside: When I created the wormhole drive for Star*Quest, I was told repeatedly that the roughly one day per light year travel time I proposed (I changed it for Space Force) was way too slow. Nobody would want to play that game, I was told. Then I read Travellers and discovered that they have a standard FTL rate of from 3 to 18 light years per week (depending on the type of jump drive a ship has). I'm quite cross with the people who told me my system was too slow.
Anyway, I feel like we need to choose something. The choice here affects the game mechanics, obviously. Naturally I like my own system, but I really hoped this would be a collaborative game and so I'm asking for ideas and opinions here. I may not have covered all the possibilities above, either, so feel free to tell me if I've missed something.