You are crew on a spaceship sent to an unknown part of the galaxy, having crossed the darkness between the spiral arm of your home region to a foreign spiral arm. You are seeking resources, allies, new technology, and perhaps things you can't even fathom In your home region, a stalemate between three factions and a lack of viable planets or areas to expand to have prompted this mission, but being so far from home, you can expect no support besides your other crew members.
The prime galaxy, and only galaxy ever visited by most sentient races, is a large spiral galaxy. It is similar to the Milky Way, but slightly larger having roughly 500 billion stars and a diameter of around 100,000ly; the prime galaxy's spiral arms are also much closer together than the Milky Way. In a spiral arm of the prime galaxy called the Regal Arm is a region around 800ly across that is generally referred to as Triune space, the triple cluster, or simply developed space. This is where the faction you're working for, the Alta Republic, has its home systems; as well as two other factions that are occasionally enemies or allies known as the Invid Consortium and the Beneficent Commune.
Most habitable planets in this region are occupied by one of these factions or by one of many allied minor factions. Attempts to expand outward along the galactic arm have found almost exclusively gaseous planets or no planets at all; attempts to expand inward along the galactic arm have been met with utter destruction by a mysterious alien race that refuses any attempts at communication, and are referred to as the Menace. In an effort to find territory to expand to, new allies, new resources or deposists of known resources a ship was constructed by the Alta Republic using newly developed advanced FTL technology to travel across the dead space between galatic arms. This ship, the Tempest, is under command of Captain Thorick, a Core Altan and distinguished officer. You will find yourselves on his ship after it has spent six months traversing between galactic arms.
Gravitational Slingshot
Ship targets any object with gravity of roughly .1-.5 solar mass or greater (dependant on ship size) within sensor range and moves at speed of .x ly per hour in direct course towards target. Minor course variance can be input with Pilot check (such as avoiding collision) before or during travel. Travel can not be cancelled without Pilot check before reaching destination, with DC based on % of distance travelled. Pilot check is always required shortly before destination or collision occurs, but at that point in travel the check is generally trivial. Ships in FTL travel are more difficult to detect the farther you are from the destination, with generally easy Perception check via sensors at the destination revealing an incoming ship.
The rules for ship combat can be found here. In general, the GM decides when starship combat begins, where the combatants are, and which way their starships are facing. This might mean that both sides are facing each other from opposite sides of the grid. However, their relative positions and facing can also be established randomly. Roll 3d6+5 to determine how many hexes separate the opposing sides. If either side consists of more than one starship, this result is the distance between the highest-tier starship on one side of the battle and its counterpart on the other. Other starships should be placed within 3 hexes of an allied starship.
Equipment from Starfinder, in particular weapons, armor, and mundane items are generally to be used in preference to normal Pathfinder items. Magic items can be taken from both sources with overlaps generally favoring Pathfinder. If in doubt, ask.
Bulk:
L= 1 lb
1 bulk= 5 lb
2+ bulk = 10*bulk - 5 lb
For these skills, Starfinder rules generally provides what can be done with them outside the obvious.
Replace all knowledges with:
Culture: A culture’s customs, laws, government, leaders, prominent inhabitants, legends, religion, history, and related topics
Life Science: Bioengineering, biology, botany, ecology, genetics, xenobiology, zoology, and other fields of biological science
Mysticism: Alchemical theory, arcane symbols, deities, magic traditions, religious traditions and symbols, and related topics
Physical Science: Chemistry, climatology, geography, geology, meteorology, oceanography, physics, and other fields of natural science
Astronomy: Astronomy, stellar navigation, FTL travel, detecting and identifying galactic anomalies
Computers (Int): You can operate, manipulate, and hack into computer systems. If you don’t have physical access to a computer system’s user interface, you must use a hacking kit to access and manipulate the system. The base DC for many of the tasks of the Computers skill is equal to 13 + (4 × the computer’s tier). These DCs may be adjusted by the GM to reflect other circumstances.
Engineering (Int): You can identify, build, repair, or disable technological devices; assess the stability of structures and machinery; and properly arm explosives. If you don’t have an engineering kit when attempting an Engineering check, you take a –2 penalty to the check.
Piloting (Dex, no ACP): You know how to drive vehicles, pilot starships, and navigate.
Every class gains either Engineering or Computers as a class skill, player's choice. For each knowledge your class normally had, you instead choose one knowledge from the above list. If you had more than 5 knowledges you gain one of Engineering or Computers as a class skill. If your class had Ride or Fly as a class skill, you gain Piloting as a class skill.
Climb, fly, swim, craft, ride.