History of the Humans
In a time barely surviving as myth, Humans were the dominant race of the planet. In this time, there were no other sentient races. Unopposed, the Humans reached untold of heights in the fields of science and magic, even blending the two in many ways. They created servant races to handle menial work and eventually even turned to modifying themselves.
Eventually their empire, as all empires do, collapsed. A combination of internal power-mongering, slave rebellions and a weave of magic stretched to the breaking point combined into a force that ultimately shattered their civilization. The freed slaves abandoned their former masters, and settled lands that fit them well.
The humans still survive, though they will never again have the sort of power they once wielded. What they are now is a far cry from what they once were, having been genetically modified by their ancestors. Physically weak, they possess thin arms, a hunched posture, and an enlarged brain. A scattered people, they mostly work as researchers and scholars. Few of the races of Solinia bear them any good will.
There are rumors, though, of Humans from the old Empire that still walk. Supposedly, in their modification of their own genetic code, they found some way to 'turn off' the aging process. If this were true, they would be several thousand years old, and in that time they have likely become quite powerful.
At the current point in time, the races of Solinia have established strong footholds, and their numbers are growing rapidly. Everything seems to be going well.
What they don't know is that one of the Elder Humans has been trying to reclaim the lands of the Old Empire. He has had some success in this, and has subjugated a number of races to serve him. This normally would be of little concern to the races of Solinia, as this has been happening on another, forgotten continent (Or somewhere else really far away that nobody knows about).
Unfortunately, he's managed to repair a reality bore- an enchanted machine that folds the fabric of reality and punches a hole through it, creating portals. There was once a network of these, but now most are broken. There is one that still works just fine though- and it happens to be uncomfortably near the lands of the major races.
From the tower housing this machine, never-before seen monsters pour forth. It's up to the races of Solinia to defend their lands, push back the monsters, and put a stop to the invasion at it's source.