Okay, here is my completely well-thought-out creature idea

The Snamu start out as hunchbacked, woolly creatures that like bugs and small mammals to eat. It would probably live in small tribes called Nemevacs, which lived in improvised shelters called Sevacs. After developing into basic civilizations, most Snamu would develop a jumpy, suspicious attitude towards other tribes, often getting into trouble with each other. The discovery of industrialization would lead the Snamu to pursue a never-quenching thirst for power, where at least one Yrtnuoc group was fighting with another through complicated internal disputes. They were a very confusing society, trying their best to find out anything about everything, whatever they couldn't figure out, they made up stories about to tell to small children and, in some cases, monkeys. They would very frequently enslave other species of their homeworld, H'Trae, for either entertainment or food.
The onset of genetic modification and single-system space travel gave much power to a single Snamu that a whole bunch were hiding out in the wilderness of H'Trae, performing experiments and creating more and more horribly effective ways to kill each other. These methods became so effective that while they killed each other with large-scale results, they also killed their own planet. At least, that's what they (if They were still alive) thought. What really happened wa that an alien race of one-eyed, pigeon-toed flying purple people eaters that frequented H'Trae got so annoyed because those darn Snamu couldn't take a hint if it blew up their planet, so they did.
There, the result of 4 hours of solid-minded thinking. Completely. Really...