Animal
The main hero is an animal. Or it includes animal as a part of the active ambiance. Or, at worst, it’s an active/passive spectator of what’s happening on the screen. In either case, those free online games include animals somehow: pandas, sharks, worms, cats, tigers, dinosaurs, rabbits, foxes, mice, zebras, cows, dogs (and other pets), chickens, and horses. You should know that nobody would call you a chicken if you play for chicken. Actually, playing for all named, you explore not only their body motions but also the features they may have, including their characters and their way of cheerfulness towards life.