Esper Genesis - A Science Fantasy/Fiction game based on the 5th ed D&D rules.

You get all new races and classes, though it's not too hard to see how some of them were derived from the originals to fit this setting. A setting where discovery of the Cauldrons, mysterious planetoid/planetary scale artifacts from an unknown source, have spawned new technologies and new powers, Esper Genesis.

Ok, it's a star spanning sci-fi romp with it's own fantasy components. Psionics and Esper powers are definitley a fantasy component that is very common in scifi. The game lends itself very well to a nice range of settings that could easily include Star Wars, Mass Effect, or even the Retief series of books if you are so inclined, though it does have it's own setting included.

I've found the writing clear and easy to understand, and the artwork astounding! In my opinion, I've rarely seen artwork of this caliber in sci-fi games, or even games in general.

It even has a good spaceship combat system that gives people things to do other than wait for the pilot or gunner to win or get everyone spaced.

If you're curious, why not take a look at the Basic Rules, that file is free. Esper Genesis Basic Rules

I own or have otherwise looked at a variety of scifi rpg rulesets for star romping, and this is one is my favorite.

As you probably now by this point, Future Core is the game mechanics & rules section of N.E.W., the science-fiction portion of What's Old Is New. The creator is really great at responding and dealing with issues, so that's always a plus to any game. On top of that, it's an interesting system that uses dice pools for tasks, and they don't get too large, unless maybe you want to recreate Bambi VS Godzilla. I and my friends haven't yet played this particular iteration of the rules, but we have played with the earlier stuff, and I've read this latest one in preparation, and so I'm definitely looking forward to it. :)

Legend is a updated version of a classic and flexible game that started with Runequest back in 1978. It can easily be adapted to almost any setting, and some examples with the older versions are Call of Cthuhlu, Ringworld, Elfquest, Hawkmoon, Elric, and Superworld among many others. To aid with this adaptability, they removed the Glorantha specific items that were always so prevalent in the other RQ versions. Something that our groups usually did anyhow as we were never fans of Glorantha.

My group is really looking forward to this, and at the current price of $1, it's a great deal that any multisystem gamer can't pass up. On the other hand, if you only ever play one game system, you really should branch out and try this.

In short it's a great game system that does not use either classes or levels and is primarily based on skills with a percentile task resolution system. Your character options for development are as wide open as your GM will allow. You want a mage with a zweihander, no problem. A sneaky little priest that moonlights as a cat burglar, it's covered. A burly monster hunter that knits his own sweaters, it can be arranged. Do what you want, not what the cliche says you have to.