Yesterday 9:06 PM
Alderson points were introduced in the Codominium future history of Jerry Pournelle and the of course The Mote in God's Eye by Larry Niven and Jerry Pournelle, a major source of Classic Traveller mojo. basically there was one point where your ftl drive worked between two stars. Star systems had a varying number of points. The explanation storywise was a FTL drive that let you pop in and out of Three Space anywhere led to planets being obliterated by raider without any chance or warning or mounting a defense. Therefore no one would buy into any interstellar government. It also shaped the strategy of the Empire of Man's space warfare. The attacks would follow Alderson points and be directed at systems with points leading to other valuable systems of course.
It was a neat drive for story writing purposes, sort of like stargates without the overhead. It also made a number of illegal, antisocial and immoral activities nigh impossible on an interstellar scale. Sadly these activities are either what player characters are up to or the bad guys opposing them. It's kind of hard for the big bad guy to run for it and cut his losses when a single warship can blockade a system. Ditto the characters trying to overthrow the evil overlord. It's even worse when you use stargates. The darn things probably are built with sensors that will give you an EEG and determine the evil centers of your brains are firing on all cylinders and then MRI your ass to tell where you tucked away that body pistol. Not fun.
The idea of unrestricted ftl access can be interesting in a post apocalyptic way. Maybe the safe older jump drives were surpassed by new ones that let you pop into our universe in the upper atmosphere of a planet and all Hell broke loose. It could be fun in an anarchistic sort of way.
Most SF settings place some restrictions on your ftl. You can't use it near a planet of star. Distance and mass varies. This lets you have a chance of sneaking around the outer reaches of a star system without letting you just pop in, slag your enemies, yell, "TAG!" and pop back out. As an alternative there may be a few dozen or more ftl points in a given star system, too many for the Navy to guard all the time.
As an alternative an FTL jump might have other restrictions than a hard and fast limit of distance. Perhaps going closer than the jump limit uses more fuel or has a longer recovery period or may damage the ship.
One wrinkle I haven't seen very often is to require the entrance and exit point to be near a star. Say you could appear around Mercury's distance from a Sol type star. this still keeps you far enough from an earth like world to allow it some kind of defense but gives you a chance to do some sneaky stuff using the giant ball of nuclear fusion for a decoy.
Another option is the erratic wormhole. A wormhole doesn't stay in a fixed location but bounces around. These could be unstable with any limits that you find interesting. Maybe some decay as other forms. At any given time a system might have several of these transient express routes and a lucky smuggler, pirate or spy might stumble onto one. Borders between polities might slowly shift as access to worlds changes. Instead of a group voyaging to the frontier, they may find the frontier has traveled to them.