Khyber, if you are still around, I'd be interested in hearing about this one.
I once ran an alternate timeline game in which Britain won the insert politically correct term for American Revolution here so that though the starships were the same, they were H.M.S. whatevers and the officers' standard uniform included a saber as well as those pointy hats (as seen on the holodeck in Star Trek: Generations).
Officers were expected to be wealthy (we never went into how) and some actually had their own vessels attached to the ship they were stationed on. My step daughter actually played the captain's daughter, complete with parasol and wrist gloves. Even to the point where she (my step daughter was 8 at the time) effected a slight British accent.
Alien races were conquered and made to join Her Majesty's Empirial Federation. Yet, after years of being a colony, the world would become a member of the Commonwealth. After years of that, they were considered to be "Britain amongst the stars."
All the tried and true races were there, as well as some new ones. The Skosians and the Eirians were two races evolved from a single race. They were parallel to Earth's Scotts and Irish. Jang Ko were a "combination" of Klingons and Vulcans based mostly on China just prior to World War II. And of course, there were the Ah-Mreens, a race of warrior mystics who plotted the paths of the stars to divine the "True Home," based very very loosely on American Indians.
Has anyone else done parallel games?