After a friend's prodding, I've decided to run a game based on the Legend system. It's relatively new, but entirely free; you can download it from the official website here: http://www.ruleofcool.com/get-the-game/
Setting and plot isn't fully nailed down yet, but it's something like this: the world's main landmass has always been split between two large groups: the kingdoms of elves, dwarves, and men to the east, and the monster tribes to the west. In the past, the two tended to get along to an extent; there were always skirmishes and the occasional small war, both between the two major groups and within their borders between the various kingdoms.
That all changed when King Reginald VII began to unify the various kingdoms under his banner, beginning a campaign that decimated most of the monster tribes. While for a time it looked like the war would be successful, and force the monsters away forever, the alliance began to fall apart when the kingdoms began to argue about who would claim which lands. Eventually, the alliance began to turn on itself, falling apart completely with Reginald's assassination.
Fifty years later, rumors of another alliance began to appear. While the monster kingdoms are strong, and have begun to retake their lands, another alliance would completely destroy them. It's up to the heroes to learn what they can of this new alliance, and more importantly, do whatever possible to ensure it never forms.
Obviously, the PCs are all going to be either members of the monster tribes, or humanoids (humans, elves, dwarves, gnomes, and so on) that sympathize with them (the latter is extremely rare though; if I allow it, it'll be only one character in the party). The monster races are unique in that they give birth to females much more often than males; only about 10% of the population are male, so the men that are born are usually well-guarded and not allowed to do anything considered dangerous, and nearly all of the adventurers are female. Monstergirls are able to mate with other humanoids however, and while their offspring will still be mostly female, male children are more common than in purely monster pairings.
The "monsters" are based mostly on the monsergirl images that have become popular lately, although the story text that goes with the images isn't necessarily canon for this game (i.e. the monstergirls don't generally go out and find men to rape, although some might). The men are similarly styled, as in "mostly human with some monster bits", not full monsters.
Character creation: Starting level 4, all classes allowed. Feel free to take an existing race and "re-theme" it as a monster race if you want, but any of the "normal" humanoid races are very unlikely to help the monsters. For stats, you can take the standard array of 16, 14, 14, 12, 10, 10; 26-point buy; or 5d6 (taking top 3) 6 times. You shouldn't have any odd numbers; if you rolled for stats, subtract 1 from one odd ability score and add it to another. If you have only one odd score left, just subtract 1 from it.
If you have any questions, feel free to ask either myself or ShadowFox.