Todd Howard told Kotaku in its latest podcast that Bethesda pitched a single-player Star Trek RPG before starting on Fallout 3.
Bethesda held rights to Star Trek games at one time, after Activision's license expired.
The proposed title was set during Kirk's time-line.
"Nothing was developed internally," Howard told the site. "There was a pitch to do a big Star Trek RPG. [But] we were doing other things, we made Fallout. We can't do everything.
"We were pondering Classic, and Shatner did voice-acting in one of the games we had.
"I want the big Star Trek RPG that you go out and explore the universe," Howard added, noting that Cryptic's upcoming MMO "fits the bill too".
You can listen to the full thing through the link.