Basic outline

The Republic has fallen! The Jedi are scattered, near destroyed after Order 66.
Darth Sidious controls what was once the Galactic Republic, now his Empire, and Darth Vader is beginning to gather power.
Unable to remain idle as his former apprentice destroys what they'd spent years defending, Obi-Wan Kenobi has come out of exile to secretly form a new Jedi Order, hoping to defeat the Sith and return peace to the galaxy.

*Rather than staying on Tatooine, Obi-Wan decides to reform the Jedi Order in secret, away from the Galactic Empire. He tracks down and protects the few surviving Jedi and recruits new ones. He also occasionally checks in on Owen and Beru Lars as they raise Luke.

*Yoda has retired from the Order and lives on Dagobah. He still mentors Obi-Wan occasionally.

*Mace Windu survived his battle with Sidious, but needed a replacement arm, much like the one Anakin had. He also has scars from Sidious' lightning. His survival is currently unknown to Obi-Wan and the Jedi.

*Commander Cody broke out of his Order 66 brainwashing and seeks redemption from Obi-Wan.

*Still loyal to Anakin, Commander Rex now reluctantly follows Vader, despite him no longer being the man he used to be.

*Ahsoka Tano is currently neutral, wielding two white coloured sabers.

*Obi-Wan has relaxed the age restriction for new Jedi, but is more more wary of forming attachments.

*Nightsisters who are willing to serve the Jedi are allowed to join if they no longer want to be Nightsisters. Most who come to Obi-Wan serve as security.