Create your own fighting animal and put it into several fights, mutations, upgrades and improving its skills.
Take one of the animals and turn it into a fighting monster defeating all the enemies and bosses. Most of the places and levels are about fighting. Simple minions, bosses or special events where you can increase damage or heal the animal by clicking on various bubbles.
Buying different skills will increase the stats of the animal and don’t forget to feed you character. You can even visit a PvP zone. The only problem is in the difficulty and getting through the story takes really a lot of time.