|"I plan to live forever, or die trying." - Vila|
Blake's 7 is a fantastic resource for the Stars Without Number RPG and Fading Suns primarily as a backstory to the default setting. The Federation, once a shining beacon of interstellar civilization, falling apart due to "The Scream" -- and the universe of Blake's 7 gives us an idea of what might have been happening in certain corners of it prior to that cataclysmic event.
Freedom fighters up against an increasingly corrupt Federation, black technologies, Orwellian methods of control, powerful alien species (including yet another variant on the Cyberman / Borg melding of computers and human-ish races), varying technology levels -- all a heady mix of elements that add some gritty texture to the often idealized future.
Of course, Stars Without Number is already pretty gritty in and of itself.
Back to the series: I particularly like the dynamic of distrust between members of the crew, and the strange cliques that emerge in such a small number of people. I think that what makes it interesting to watch now, despite the slow pace compared to today's shows, is the evolution of trust between characters. While it echoes the dynamic of Firefly / Serenity, I doubt that one can consider Blake's 7 a 'family' in the same way that the crew of Firefly / Serenity came across.
Perhaps the mechanics of the Cold City / Hot War RPGs would be appropriate?