Science fiction is a natural fit for a roleplaying game, and, although medieval fantasy still has the largest draw, there has been a steady increase in the number of MMORPGs with a sci-fi setting. If laser-beam toting superheroes are more your style than elves and dwarves, these science fiction MMORPGs feature persistent worlds full of high-tech weaponry, spaceships, and belligerent aliens. The list is based on your feedback, among other things, so I'm always open to suggestions.
The Good vs. Evil Edition includes both the original City of Heroes and the follow-up, City of Villains. Although relatively simple for a game of this kind, it has a low learning curve, a fast pace, outstanding character creation, and it's a refreshing change for those of you that are weary of medieval fantasy settings. Become a super hero in Paragon City, or pursue the life of a master criminal on the nefarious Rogue Isles. The game has been regularly updated since launch, and now includes missions with destructible enviroments.
Eve opens up a massive online universe in which your spaceship is your best friend. You can mine, battle pirates, be a pirate, or aspire to greatness within the game's corporate structure. This title has seen steady improvements over the years which have pulled in a lot of new players, and the economic component is unsurpassed. Note that the skill system is time-based rather than deeds-based, which is a major departure from most RPGs. It isn't for everyone, but there's nothing else quite like it.
The aliens have landed and forced humanity to take refuge on a distant planet. The future for our species looks grim, but we're not about to go down without a fight, and we have found some friends out there. Richard Garriott's Tabula Rasa uses a mix of FPS and RPG to keep you in the action, and puts you in the middle of an ongoing war where NPCs try to control territory. Not an overly deep game, but worth consideration if you'd like something different.
Launched in 2003, Star Wars Galaxies has seen more dramatic changes in it's lifetime than any other MMORPG I can think of. The "New Game Enhancements" which were implemented in late 2005 were particularly controversial, and created an enormous ripple in the game's community. Although some features from before the NGE have been revamped and put back into the game, it clearly hasn't been enough to satisfy many former players. Still, SWG encompasses everything from infantry battles to space combat, and it's the only persistent world based on the "Star Wars" universe.
Battle other players or mutant monsters with a wide variety of high-tech weaponry in this futuristic RPG. Characters have a lot of flexibility and advance based more on which skills they choose than what class they are. It offers an interesting combination of socializing, customizable missions, and player on player combat. The graphics are getting a bit dated, but the basic version can now be downloaded and played free of charge.
Sony Online Entertainment took over operations of this MMORPG based on "The Matrix" in 2005, and they've made various changes that seem to have been well-received. It doesn't come with a cortical implant, but you do get to hyperjump onto tall buildings and perform lethal blows in "bullet time." Although they've tinkered with the combat system quite a bit over the years, the game still hasn't managed to find a very large audience.