With Leonard Nimoy's Spock proving extremely popular with audiences, Paramount had a desire to build on that success after Star Trek's cancellation. Their idea; a show set on Vulcan with Spock returning to the planet to be with his own people. It would have had a very different feel to Star Trek and it is hard to imagine that it would have been that successful either. A cast of aliens with no emotions would have made it difficult for the show to have any semblance of drama. Perhaps that is the reason Gene Roddenberry turned down Paramount's offer to produce the series. Unless Spock took a radically different route - his human emotions battling against his Vulcan side - it wouldn't have been a very engaging prospect for audiences. Spock was better served alongside Kirk and McCoy in the continuing adventures of the USS Enterprise on the big screen.