Critters will make noises when hungry but won't die if not fed. However, not feeding a Critter will cause its traits to decay faster.[Verification Needed] Critters will get hungry after about 2 to 4.25 days. A Critter can be "petted" by clicking on it, triggering a small animation. Feeding any Critter Glow Berries or Lesser Glow Berries will make them have a temporary light radius.
Each player can only have one Critter at any given time. To get a different Critter, players must "Abandon" their current one by being near the Rock Den and right-clicking that Critter.
A Mothling is a juvenile version of a Moon Moth. Mothlings can be obtained in exchange for a Moon Moth and Flower Salad. Unlike other critters, which have no function, Mothlings can act as a light source. A Mothling will not give off light when hungry.
Critters can have traits which determine their behavior. Player actions add or subtract points from one of the Critter's traits, depending on the action, with the trait having the most points becoming the dominant trait and an adjective is shown in the Critter's name.
A Critter's first dominant trait is determined after 10 days of obtaining the Critter, and dominant traits are reassigned every 1.75 to 2.25 days.
Trait points decay at the rate of 1 point per day. The maximum amount of points a Critter's trait can have is 40, while the minimum is -12. Should all traits on a Critter have a negative point value, the Critter will revert to having no traits, and the next dominant trait is assigned after 3.75 to 4.25 days.
Performing an action that adds points to a trait that is already the dominant trait gives a 10% bonus to the points added to that trait.
The Playful trait is given to Critters when the player pets them and when they play (either by themselves or with other players' Critters).
The Playful trait adds the adjective "Peppy" to the Critter, increases the range at which they play with other Critters, and makes them play more often (effectively decreasing the rate of point decay, since playing adds points to this trait).
The Well-fed trait is given to Critters when the player feeds them. The points added to the trait are affected by the Food's freshness and its type and if it's the Critter's favorite food. Fresh food gives the full value, Stale food gives half (50%) of the value, and Spoiled food gives only a tenth (10%) of the value. All Crock Pot dishes give 4 points, while other food gives 1 point. The Critter's favorite food is the food item used in order to adopt it, and feeding a Critter its favorite food gives 5 points to this trait.
The Well-fed trait adds the adjective "Plump" to the Critter's name and makes them get hungry less often.
Critters were added in the Cute Fuzzy Animals update, except for the Giblet added during the Year of the Gobbler event, and the Mothling added in the Turn of Tides update.
The Kittykit's name seems to be a mash up of the name for baby cats and baby racoons, "kitten" and "kit", as well as a play on the term "kitty cat".
It used to be called the Kittycoon.
Despite their name, the Vargling's appearance is more similar to the Hound. Furthermore, Wigfrid refers to it as a hound and they are made using Hound's Teeth.
Wickerbottom refers to the Vargling as Canis lupus which is the scientific name commonly referring to the Gray Wolf. Suggesting that the Vargling, and to an extent the Hounds and Varg, are related to said wolf.
The two skins added for the Vargling during the Chinese New Year event Year of the Varg, alludes to two dog breeds that supposedly originated in China; the Chow Chow and the Shih Tzu.
There is an extra function in the Critters code called "IsSuperCute", which does nothing except return "true".
Strangely, feeding a critter Rot or Rotten Eggs stops its hunger cries, despite them making players lose hunger points.