Puddles is cute science.

Puddles gives you control over a behaviorally-based aquarium of water plants and fish. You control the size and speed of your fish and you decide what behaviors they express. By mastering the behavioral stack, you can construct your Puddle any way you see fit.

Create a peaceful pond of herbivores living in unity, or a vicious sea of carnivores who must eat or be eaten. Master the art of balance and perhaps you can create a Puddle biome containing both herbivores and carnivores in equilibrium.

Fish, plants, and water:
An aquarium in your hand, Puddles is a world all your own.