Good table-top sci-fi rpg.

[thecretanhound]

Traveler-Space Traders/Mercenaries/Smugglers

Eclipse Phase-Transhuman Space Adventure

Interface Zero-Cyberpunk Dystopia. Has psionics, but its scientific, not magic.

Gamma World-Post apocalypse with lots of mutation.

Chris Perrin's Mecha-Generic Mecha Game

Heavy Gear/Silhoutte Core-Military Mecha

Gear Krieg-Alternate history WWII with walking battle tank mechs.

Doctor Who: Adventures in Time And Space-Doctor Who, if you don't know what that is, I can't even

Numenera-Weird post post post post apocalyptic world that has seen the rise and fall of 8 great civilizations over billions of years. It has "magic" but the magic is actually old technology that the people who use it barely understand, nanomachines in the air, a datanet flowing around the world on microwaves, that sort of thing. Basically, the people who live there believe in "magic" but its really just super advanced tech. Weird Scifi. Its an interesting setting.

<===TTRPG Nerd

Some great games listed above, Firefly also had a great RPG setting as well, Cyber punk RPG, Jovian Chronicles (same guys as Heavy Gear (The DP9 silhouette system is my favourite system rules set to date)   D20 Future, RIFTS ( A HUGE SCI FI WORLD of books (rules are ok)  Robotech great cartoon plus RPG setting same rules as RIFTS.  Oh and Star Wars is always fun. 

 

[Arkane609]

MechWarrior by Wizkids. Though its more of a Wargame rather than an RPG.

There's also WH40k: Space Hulk if you want a dungeon crawler game.

Hell, I even crafted my own Sci-fi version of DnD since none of the official ones satisfied me.

 

[Kraynium]

Omega Connection is what you are looking for....