There's no shortage of interesting games that I want to play at least once for various reasons: the setting, the system, the possible stories, etc. While these things tend to bounce around across various genres, I decided to build a list of RPGs I'd like to try out and limit it to one genre for focus: science fiction.
I've played in and run the following games: Star Frontiers, Traveller, West End Games's Star Wars RPG, Cyberpunk, and Fading Suns.
As for games I'd like to try out the following:
Starblazer Adventures - not so much for the setting, but for the game system. It seems to be a far more narrative-oriented system in terms of game mechanics (essentially the same family of FATE rules as Spirit of the Century), but I can't quite wrap my mind around them by mere reading. As for the setting -- I've never read these comics, but they seem extremely pulpy and sadly not my type of pulp science fiction. If I had to run it, I'd have to tweak any and all of the settings to some thing more to my science fiction tastes.
X-Plorers - partially for the setting, partially for the system, partially for the novelty! X-Plorers is a "what-if" RPG, one that asks "what if the first RPG had not been influenced by fantasy novels of the era, but by science fiction novels of the era?" Not quite imperial science fiction, not totally hard science fiction, and definitely not pulp science fiction, and it's got character classes and levels, but skills as well. Free to download, too.
Eclipse Phase - wanted to try out transhuman science fiction gaming ever since GURPS Transhuman. Eclipse Phase, with its fantastic production values, and its "Revelation Space meets Global Frequency" pitch and percentile-based game system have piqued my interest as well.
Here's hoping I get the chance in the next year or so.