Apparently the branching main story (replete with 16,000 lines of dialogue, so say Radian-Helix) isn't quite enough, so they're aiming just that little bit higher. The developers will be looking for beta testers soon to help work out any kinks before the final release, as well as help them flesh out the mod with some side-quests.
Right now, the main quest of Fallout: New California is finished - present, correct and playable from beginning to end. Within, a quite dramatic announcement trailer featuring some decent enough amateur voice-work and a whole lot of shooting. Originally announced in 2010 as Project Brazil, Fallout: New California is effectively a whole new Fallout game built on top of the New Vegas engine by modding crew Radian-Helix Media, and it's due for release on October 23rd. While the recently announced Fallout 76 might be diverging from series standards, it looks like fans of traditional dialogue and roleplaying-heavy Fallout adventures won't be entirely left out this year.