The sci-fi drama, which starred Hermione Norris, Liam Cunningham and Eric Mabius, was cancelled by the BBC last month, following a decline in ratings.
Richards told Den of Geek: "We had a huge episode one planned, which was a kind of battle for Carpathia. It was a battle that was fought on a number of fronts, and involved some causalities among our main cast."
He continued: "There was [also] Fleur (Amy Manson) with the ACs, and her relationship with Rudi (Langley Kirkwood), that was only hinted at. So, we had all that to deal with."
Richards also confirmed that future episodes would have introduced a "populist character" who
was "the absolute opposite of anyone we'd ever seen on Carpathia before".
"[She] was going to be the female commander of CT-10," he explained. "She was going to be terrifying. She was going to be [like] Ian McShane in Deadwood. She was going to be an absolute no-nonsense, kick-ass character."
The showrunner also announced that Outcasts could continue in another form, following the BBC axe.
"I'm very keen on doing a novelisation of the 'missing' series, because we had brilliant stories," he said.
The first series of Outcasts is now available on DVD and Blu-ray.
> Outcasts writer responds to critics