Copying some things over from the discord:
There are several things that are important to consider when designing your creature: stats, attributes, specials, and behaviors.
The stats are: size, power, speed, stealth, intelligence, defense, and HP. Each one of these relates to how advanced your creature is. The stats are fairly straight forward, but if any need further explanation let me know.
Attributes are elements of your creature you increase directly. These are normally related to the senses (sight, touch, smell, taste, ect.). For the example of sight, increasing the attribute will give you generally slightly better eyes. Using a special to give them heat vision or extreme farsight would be specials, which have more specific effects. Poison and venom are two unusual things that fall under the attributes section. As too do resistances of all kinds.
Special traits are particular evolutions from the trait list. These are special physical traits that your species has evolved. These traits often effect your base stats, or can give special abilities. For example, if your creature develops claws, that increases your power slightly as well as allowing your creature to inflict slashing damage.
Behaviors are specific things that your creature does. With no behaviors, your creature will simply sit there and starve to death. Some are going to be quite common, such as food searching behaviors. They're meant to be fairly specific ("Search for the ___ foodsource" rather than "Eat food."). Your number of behaviors is limited directly by your intelligence.
Trait Costs
Increase stat: (Current number of stat -1)
Increase attribute: (Current number of stat)
Add set of limb: 2
Invertebrate: 5
Vertebrate: 10
Endotherm: 5
Exotherm: 2
Simple Lungs: 3
Simple Gills: 2
Upgraded respiration: 4
Carnivore: 3
Omnivore: 5
Herbivore: 4
Ruminant: 3 (Prerequisite: Herbivore)
Scales: 2
Feathers: 3
Fur/hair: 2
Coloration: 1
Claws: 3
Hooves: 3
Fins: 2
Tail: 4
Chiton: 3
Armor plates: 4 (requires chiton or scales)
Quills: 3 (requires fur/hair)
This trait list is currently (and most likely eternally) being added to. If there's something you want priced, let me know.