The first multicellular ancestors of this species developed in the oceans- trilateral symmetry came to be the normal body plan in these primordial waters. Swimming by means of bodily undulations, the early lifeforms on this planet most closely resembled thick-bodied jellyfish. Some developed into benthic, armoured creatures, others developed into the wide variety of aquatic niches available. A food web, supported by simple red or purple algae, gradually complexified. Some species began to cephalize, their central regions growing streamlined, with three long, segmented limbs twisting through the water behind them. One particular branch in this long-limbed phylum, Triartidae developed into an effective variety of carnivores, using their trilateral, tulip-like mouths to capture swimming prey or break open armoured bottom-dwellers.
As the invasion of land got underway, led by simple photosynthesizers and pursued by simple armoured trilaterals, some of the Triartids began to exploit the situation. Some developed their segmented limbs to use like tentacles, pulling prey from the land into the water. It would be many more millions of years before some Triartids would begin actually moving into a full amphibious lifestyle.
As plants on land grew larger, spreading hospitable regions further and further inland, some members of the Triartid phylum began to spend time out of water, sluggishly hauling themselves about with their prehensile limbs. These land-dwellers would later become known as the class Vinculidae.
As the Vinculids became more adapted to life on land, they developed a considerably more effective means of locomotion, moving in an undulating, spinning manner, holding their heads above while their limbs twisted around below, pushing and pulling to move the creatures forward. A secondary set of jaws which had existed only vestigially in the aquatic Triartids began to develop into powerful crushing implements, the primary weapon of the creatures in their hunt of their slow, but hardened prey.
As terrestrial life continued to develop and flourish, increasingly elabourate forms of movement continued to develop. As an extension of their rotational motion, some Vinculids began to ‘run’, in a sense, putting their weight only one limb at a time as they rotated their bodies through the air, like a wheel and axle balanced at a 45 degree angle.
Their prey species began to diversify- some small shelled creatures became faster, or took to the trees and the air, while closer Vinculid relatives, having to herbivorous roles, found themselves on the menus of their predatory cousins. Massive evolutionary arms races ensued as the environment grew ever-richer, warm, wet and thick with oxygen.
Around this point, however, just as Vinculid diversity was peaking, a devastating meteor impact brought an end to almost all complex life on the planet. On land, the only surviving species were a few tiny Vinculid Omnivores, a handful of hibernating armoured creatures, and a handful of saprophytic photosynthesizers. The world was only beginning to recover when a new massive die-off struck down life once again. The period was brief, but saw the devastation of the local ecosystems, dramatic atmospheric changes, several crust-shattering impacts. Judging from the scattering of countless artefacts believed to be of a technological nature around the planet, it is believed that this was an aborted colonization attempt.
While this mysterious event did not deplete planet’s geological resources, it still left many major legacies- the massive, glassed craters which survive in some form to this day, or the dramatically reduced sea levels and reduced atmospheric pressure, but possibly most important is the alien ecosystem that they brought along with them. While most of the introduced species died off very quickly after the incomplete terraforming, a few hardy survivors managed to adapt to their new conditions, and thrive. While this group was composed mostly of microorganisms and a handful of tiny, amorphous scavengers, the most important survivor was the strange, fleshlike mesh which spread, at several points in history, over much of the world. The red mesh had root systems and photosynthesized, but also exhibited many detritovorous animal behaviours.
Throughout all of this, the Vinculid family survived at the very edge of extinction. When the global recovery began, they were a simple, adaptable group poised to explode in the massive variety of niches. In a geological blink of an eye, they predated upon and outcompeted almost all of the introduced species, becoming the dominant form of life for the first time in their evolutionary history. Faced with a massive amount of alien mesh, it was a Vinculid species which first developed the digestive abilities to handle the material, finally bringing it into check. Even where the mesh was overgrown, the flexible locomotion of the Vinculids provided them with a great advantage in manoeuvring through the twisted organic maze.
With the world intact once again, our attention turns to a particular Vinculid order, a collection of social omnivores, Veredidae. Living alongside their mesh-grazing cousins, these creatures were fiercely territorial, and had developed skilled hunting techniques, specializing to life outside the twisted biological maze. Their segmented limbs widened into flattened, paddlelike shapes, while the tips each developed two tough spikes, to help grip and bring down larger prey. At the same time, the species’ visual and olfactory senses continued to improve, matching its similarly developed physical capabilities. In the family Dextralabrum, the mouth has bloomed into a whole new level of complexity. From within its beak, a tripartite tongue could emerge to catch and drag in meat, while its outer jaws developed into a cluster of three manipulating appendages, usually used for grooming, social and hunting behaviours.
These creatures thrived through a period of great stability in their world, growing diverse and raising their territorial competition to very high levels. In this air of life-and-death rivalry, the first tool use began among some Dextralabrid genii, simple sharp stones used in hunts or tribal warfare. Emerging victorious from these harsh evolutionary struggles was the genus Latuiunguis, a species standing roughly 1.5 m tall, with a particularly well developed brain and nervous system, simple linguistic capabilities, dextrous tool-using capabilities, and retractable claws on its segmented limbs. The genus Latuiunguis quickly became dominant in its small, native continent. Developing increasingly complex tools, the various tribes of the species Latuiunguis callidus developed weapons, tools for harvesting the mesh and other sessile life, and even simple fortifications.
This species’ society would have likely stagnated around that point, had it not been for several sudden and dramatic shifts in climate, which caused two very important things. Firstly, it pushed many tribes into an adapt-or-die situation, and secondly, it opened up a land bridge between the species’ homelands and the supercontinent that made up the rest of the world. Their stable world radically changed, the disoriented Hletho, as they called themselves, spread throughout the world, exploding in cultural diversity and population. Religions, of a sort, appeared to explain their strange new world. A great variety of supertribes eventually developed into a collection of countless principalities, engaging in trade of goods and warfare between each other. The mesh- Thotha, in the language of the Hletho- provided a constant, if limited, supply of food, and development was driven by a simple instinct to compete, as well as a complex system of familial honour and debts.
Thus, the Hletho did not come to form ‘empires’ as much as they formed a complex system of alliances, which would regularly shift due to various fulfilled promises, broken vows, and the like. A variety of religions came and passed, but over time a general belief in a great familiar birthing ancestor became widely accepted throughout the civilized Hletho principalities.
It should be noted that, while in the pleasant equatorial regions civilization was flourishing, the more harsh and variable northern regions, particularly those away from the water, were roamed by nomadic tribes typically viewed as inscrutable and violent by their settled counterparts.
In this environment of diplomacy and intrigue, technology slowly progressed. Stone gave away to metals, which were succeeded by newer and newer material technologies, in a roughly similar fashion to the development of humans on earth, albeit at a significantly slower speed. Interestingly, the idea of recording their language on a solid medium did not occur to the Hletho until comparatively recently in their civilized history- they possess a tremendously rich memory, and transmit information verbally. With the development of ‘memory machines’, new levels of thought, development and communication became available. Much of the world- Thaej, as it is known to the Hletho- became connected by new electrical information networks, and new levels of global interaction began to arise.
Over the last several thousand years, the Hletho have begun to explore upwards, out of their world. Something of a rift between those who wish to expand, and those who do not, perhaps fearing a massive societal upheaval much like the one in their ancient past, where they first left their small island to see the great world.
Experiments in simple space travel have gone on for many generations now, and it is only recently that Hletho Physicists and Engineers have completed the construction of the ‘Compaction Drive’, a superluminal transportation system which compacts a linear section of space in front of a vessel and stretches the space behind it, allowing a vessel to travel tremendous distances without having to travel at relativistic speeds. The galaxy awaits!
Otherwise, bug race is a bit cliche (no offense!), but acceptable if only because they're almost obligatory to science fiction 
Take your time, you've got 'til Wednesday to get it all written up. I just want to say that you should drum up quite a bit of flair and detail, so that they're not just lizardmen. They can be reptillian humanoids, that's fine, but just... you know, big, mean lizard guys is about as much of a cliche as swarms of space-bugs are. But I digress, and you guys ultimately can make whatever you want 
lol
