Welcome to lands of bloodshed and chaos, where new civilizations rise and fall from the whims of gods, and the clash of blades. Well, first things first of course, the world these struggles happen. The gods were tired of watching humanity, the grand creation of mother nature, wanting their to not watch another's triumphs, but mould their own, wishing only to further their own power, wanting to be the next big fish. The gods that came together were far from strong enough to create new worlds by themselves, and thus made a truce between them. They would each form their part of a world, where their owns creations roamed, the lands however they saw fit. The pieces of the puzzle complete, they placed them together, a new world crafted from their combined might, an achievement they could all revel in. Though their lust for power never fled, and their greed did not just want the part they had crafted. The lands broke into war, the gods sending their creations to butcher each other, the last man standing left to claim the world as their own, and cast the other gods into the abyss. You play as one of these many gods fighting over this world, your people shaped in whatever twisted way you can think of, and they await your command, ready to wage war in your name.
This idea's still completely changeable, this just being something to get the brain ticking. Making your own race, you also get to choose the geography of your part of the world, which will inevitably leave to some quite interesting climates, and ones that should make sense for what lives their, and reachable by ground to make it balanced unless everyone has some form of air transportation, such as bird men using their natural wings, lizerdfolk riding dragons, etc. Don't make races too ridiculously powerful now ether, or if you are expected to have very few of them, so for example say pete has made his main race as huge giants made of titanium. He's going to get only one of them, and its techs going to be as complex as trying to punch you, and because of its ridiculous toughness and power, gods can actually just go up to it and punch it in the face, as it lacks any kind of resistance to keeping them far away, out of their reach. Oh yes, nearly forgot some things. You also think up the wild life for your area, and make them interesting too, and actually adapted to their climate. You can also choose to have one or so "lesser" beings, think of goblins for orcs and kobolds for dragons, that kind of thing. Gods can also do some funky stuff too depending on what they are the god of, and also affects what beings their allowed to create. For example, the god of storms would have beings made of crackling lightning or water, or something else themed around lightning, thunder, and stormy weather, and able to do such things as throw lightning bolts onto foes below, and cause massive winds to halt advances and even blow some lighter creatures away. These will obviously have limits, so as not to have gods just spaming their death powers everywhere and making elite troops worthless. I've still got more idea's for this, and its all still workable.