Setting:Brighthammer 40,000/Zoanthropes

Long ago in a distant galaxy, a race called the Zoanthropes focused upon molding, shaping, and creating the greatest biological technology known to the universe. They were highly successful -- in fact, they were too successful, as their genetically engineered slave races, all highly adaptive in order to suit their needs and every whim, eventually rebelled.

The result was the Tyranids, a viral ecosystem that consumed their entire galaxy, and another one.

Now the last remnants of their race flee to the Milky Way, with the Tyranid swarms in hot pursuit. Having learned nothing from their mistakes, they seek new biological information, new power, new allies, and a chance to rebuild their empire and stop their creations- and possibly create a more reliable slave race to replace their failed experiment.