The "Open Gateways" RPG system is a pen &paper gaming system (that is a hybrid of d20 systems and the newer 4E rules) that removes tradition classes from the game; instead players choose Gateways, which are multi-branched tree structures of Skills, Talents and Powers of like abilities. The further down the trees you get the more powerful the abilities are.
These Gateways function as mini-classes that can be combined in any ways that the players want; it forces choices when a character improves, but no longer are they forced to surrender every Feat they get to complete their ability to attempt a multi-class. Your role as a Striker, Defender, Controller or Leader is now separate from your class and implement, these can be mixed and matched in any possible way you choose.
See Character creation blog post or more detail, also in blog are many other details about game system : http://opengateways.blogspot.com/2011/08/character-creation.html
Also, this system allows choices between improving Hit Points and gaining another Feat, or improving Defenses or learning a new Power. It also allows characters to attempt more actions in a of round combat, so rather than being restricted by the "Standard, Move, Minor" actions, players can now role-play during combat and attempt to "do more", but at a penalty.
Experience is now split, so two pools. One is for Role-playing type abilities that add little advantage to combat, except maybe by creative players. The other pool is for weapon and combat centered abilities. This way players actually may choose the Feat and abilities that are most often pasted up to increase their combat survivability.
In addition to rules alterations and streamlining a large catalog of new items are presented, which include an elite category of weapons, black-powder items such as grenades and the Double-Barreled Dragon's Breath, also crystal socketed items, runic items and interesting cursed-blessing items. Many other modifications have been made such as Mana Pools, Double Daily Powers, snap and triggered rituals, faster paced encounters with longer lasting effects, and reclassification of skill challenges.
Combat is deadly and faster paced, immobilization now actually has a combat penalty, and there are more situational modifiers and penalties. Defenses typically don't rise into the 30's; but neither do the attack modifiers: more things hit and more things hurt, so encounters are resolved faster.
Additionally, a feeling a realism is applied to the game (keyword being "game"; I realize it's fantasy, but it still can be internally consistent), and the players and the game-master are encouraged to simply veto or alter things that just don't make sense, rather than simply saying, "I guess, that's what the power says...".
From the campaign setting, In the realms of Kraterra, the Land of the Crater, in the year 2655 of the God-King...
Far from the Dust Sea, from the wasteland of the Frozen North, he came. Dragging a trophy, the head of a once powerful demon-lord...A man, resistant to the powers of the Hellions. He knew not his name, nor his origin, all he knew was his hatred for the Horrors of the abyss.
None could argue at his skill in battle with the demonic creatures of the abyss that plagued the realms for over two millennia. A following began around this champion, who could finally take the fight to the hordes. No longer did people have to rely on their ability to remain hidden from the Hellions. No longer did they have to be forced to sacrifice their own in pathetic attempts to keep the hordes appeased. No longer would the allies of man be forced to simply survive, they could live once again.
He began to lead them, first hundreds, then thousands. They came from the ruins, and forests, from the mountains and caves, where they’d been hiding and surviving for over 2,000 years. The clans of Humans, Elves, Dwarves and others races came together to begin to rebuild their once great empires as a unified force in wake of his man...this champion...This Emperor of humanity.