An underwater ecosystem in the game Ecosystem, showing a dark cave entrance, a creature, and plants.

An underwater scene from the game Ecosystem, featuring rocks, plants, and sea creatures.

Ecosystem game screenshot: underwater scene with rock arch, blue light, various menu icons, and a mini-map in the corner, sand floor

An underwater scene with marine animals, plants, and rocks.

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The world is your aquarium in Ecosystem, a world simulator where you can watch and influence the evolution of marine life. There are no predetermined creatures in this game; every single one will evolve on its own.

All in-game life forms have simulated DNA and will evolve over time. Their entire body from skin to the skeletal system is dictated by their DNA, as is everything about their behavior, from the way they swim, feed, and seek mates.

Over time, their genetic code can mutate or even combine with those of other creatures. You can also alter their genetic code at will to create weird and fantastic animals.

The game takes place in an ocean where all movement follows pre-determined physics. The fish will actually swim, using their bodies to propel themselves as any marine creature would. Combined with evolution, you will see incredibly varied ways for these fishes to swim. In fact, due to the amount of evolution in the sea, you may never come across the same life form twice in Ecosystem. You can spend hundreds of hours watching these animals feed, grow, mate, produce offspring, and evolve.