These are all canceled episodes of Star Wars: The Clone Wars (2008) Season 6. The episodes "A Death on Utapau", "In Search for the Crystal", "Crystal Crisis", and "The Big Bang" had the production codes 6.01, 6.02, 6.03, and 6.04, respectively. The episodes "The Bad Batch", "A Distant Echo", "On the Wings of Keeradaks", and "Unfinished Business" had the production codes 6.09, 6.10, 6.11, and 6.12, respectively.
A story arc with the production codes 6.05, 6.06, 6.07, and 6.08 would've seen Ahsoka teaming up with the Martez sisters for a deal with the Pykes. This story arc was released as part of Star Wars: The Clone Wars (2008) Season 7.
A story arc with the production codes 7.05, 7.06, 7.07, and 7.08 would've seen Asajj Ventress teaming up with Quinlan Vos. The story arc was novelized by Christie Golden as part of the novel "Dark Disciple". The episodes would've been called "Saving Vos, Part I", "Saving Vos, Part II", "Traitor", and "The Path".
A story arc with the production codes 6.21, 6.22, 6.23, and 6.24 would've seen Darth Maul forming the Shadow Collective, a criminal organization composed of the Hutts, the Black Sun, the Mandalorians, and some fearsome Nightbrothers. The story arc was adapted by Jeremy Barlow into the Darth Maul: Son of Dathomir comic mini-series, which was adapted from the scripts written by Aïda Mashaka Croal and Matt Michnovetz. The episodes would've been called "The Enemy of My Enemy", "A Tale of Two Apprentices", "Proxy War", and "Showdown on Dathomir", respectively.
An unreleased story arc with unconfirmed production codes would've seen Rex and R2-D2 crash-landing on a moon of Ryloth. It was written by Brent V. Friedman.