I suppose this is the official forum for this game, at least for now? In any case, I had an idea for a race and, seeing that others suggested races here, thought that I should post my idea here. I hope to hear your thoughts and refine my concept with even better ideas.
I wanted to design a desert-dwelling race that was unique and interesting. After some deliberation, lizardmen seemed the best option. Although this concept might be overly long and detailed, I think that it merits extensive explanation.
The reptilians have a mix of features from many reptiles, though the largest influence was komodo dragons. Think of reptilians as bipedal komodos. Real komodos can stand on their hind legs briefly, and they look pretty goofy doing it.
Reptilians are ectothermic and therefore can only live in cool in environments with great difficulty. Cold areas (particularly below freezing) are uninhabitable for them. However, reptilians can lie dormant and nearly motionless, allowing them to live in areas which are warm in the summer and cold (but not freezing) in the winter, as they can remain inactive during the cooler months. Because they do not have to generate their own body heat, their metabolism is very low. They can thus live without food for long periods, much like crocodiles. If the ambient temperature is high, they can devote a much higher proportion of their calories toward purposes other than thermic homeostasis. This makes them specialized for warm environments, but reptilians prefer no particular warm environment. Thus, reptilians are selective generalists, able to survive so long as the temperature is high. Clothing is not especially important to them, as they have little body heat to retain and their scales already offer protection.
Reptilian metabolic versatility has a significant cost, however. Nervous systems, and particularly brains, are energy-intensive and require relatively high metabolism to maintain. Lacking this, reptilians do not develop large brains and are therefore quite unintelligent, though they still are among the intelligent races. If humans have an intelligence of 100, then reptilians are somewhere around 60-70. They thus tend to be more feral than civilized. They are capable of hunting/gathering and herding, but achievements of greater intellectual fortitude (cities, complex governments, infrastructure) will likely elude them or only be shallowly developed. However, reptilians can easily live for over a century, again due to their low metabolism. Thus, individuals can accumulate knowledge, so reptilian civilization is certainly not impossible.
The largest reptilians can be monstrous, but many are not significantly larger than a human. A reptilian's size is largely determined by the available nutrition during its maturation. Reptilians living in remote deserts with scarce food will be smaller, while those dwelling in lush and hot jungles will be mighty beasts. The reptilians are very tough (due to muscles and thick, scaly skin) and capable of high strength and agility, but only in short bursts. They thus have low endurance. Low metabolism means that signficant time is needed for an exhausted reptilian to recuperate, but a fresh reptilian can easily crush bones. Their dexterity is also quite low, as their hands are akin to those of komodo dragons: thick, ponderous fingers tipped with large claws unsuited to fine manipulation. Reptilians are obligate carnivores. They find plants indigestible, but livestock can consume them, thereby transforming plants into meat. Reptilians are bipedal and terrestial. Though they are not unimpressive swimmers, their low stamina renders them unable to traverse long aquatic distances.
Whether r- or K-selection is prevalent depends on the circumstances. The number of eggs laid by a female is determined by her nutrition. In times of plenty, when she is well-nourished, she will lay many eggs. In times of scarcity, she will lay only a few.
Reptilians use the ZW sex determination system, which can be seen as the opposite of the mammalian XY system. Among humans, two of the same chromosome (XX) produces a woman, while differing chromosomes (XY) produce a man. The Y chromosome is smaller and modifies the X, meaning that the base form is female and men are modified women. In the ZW system, two of the same chromosome (ZZ) produces a male, while differing chromosomes (ZW) produce a female. This means that the male is the base form and females are modified males. This is significant because it allows parthenogenesis, i.e. reproduction without fertilization. Komodo dragons are an example of this; a female can lay eggs which will hatch into males who can then mate with her once they are old enough, thereby producing more females to create a stable population. This functions because the female (ZW) can produce offspring by herself with either ZZ or WW chromosomes. WW is not a viable combination (like YY among mammals), so only the ZZ (male) eggs hatch. Their Z chromosomes can then combine with the mother's W chromosome. Among mammals, females only have X chromosomes, so a parthenogenic mammal could only produce daughters. This could lead to interesting cultural conflicts in the game wherein reptilians do not disapprove of incest while other races find it barbaric. This sex determination system also means that reptilian populations are extremely difficult to displace, as even one female can eventually produce a stable population (though with a severe genetic bottleneck).
I imagine reptilians inhabiting uncivilized equitorial regions such as jungles and deserts. They are exceptionally well-suited to hot environments with widely varying food supplies. Places that would fry other races would be comfortable for reptilians, meaning that they could continuously inhabit certain areas without ever being displaced, as no other race is interested in those areas. Thus, they are left and can develop low-intensity civilization. Perhaps there could even be the odd reptilian who is super intelligent. This could combine with the long lifespan to create a powerful leader who brings about a golden age of reptilian might based on a fertile river or desert oasis.