Maybe not a computer game, but there is a board game by Agents of Gaming, called Babylon 5 Wars. AoG was closely associated with ADB, and thus Bab5Wars bears some resemblance to SFB. They had a huge line of miniatures; hundreds of ships for every race in the show. (Even the non-aligned worlds.)
Sadly, I think AoG went out of business last year. With Bab5 off the air for 5 years and no new movies etc coming down the pipe, the game finally fell below the threshold of profitability. But you can still find the game and the miniatures and I guess that you will for a year or so.
-S'Cipio