EEvol

EEvol is a simulation of an ecosystem of individual cells and their organelles. Cells begin with random DNA, and 99% of it is not viable, so most cells die quickly. The simulation explores how single-celled life competes and adapts, and how multicellularity can emerge without assigning cells fixed roles.

From simple cells to competition

The first viable cells appear in a world rich in gas bubbles, which they can break down for energy. Early cells need only an organelle for processing gas and a DNA instruction to multiply. As cells spread, competition for gas increases; some begin extracting energy from dead cells, while others grow flagella to reach areas they cannot access by passively riding the water flow.

The simulated physics can create barriers to life. Some cells evolve to swim upstream into dense flows of gas bubbles, specializing in smaller bodies and stronger flagella. Later, some cells release biomaterials that accumulate into physical barriers, much like stromatolites. These materials can be broken down, but doing so costs energy, unlike consuming gas bubbles or dead cells, so they build up. Biomaterials appear as colorful circles with a square in the middle.

The rise of multicellularity

In strong currents, even multiple flagella may not provide enough force. Some cells remain together after dividing and support one another, forming early multicellular life. The simulation is designed to let each cell perform multiple functions and choose which organelles to grow, rather than forcing multicellularity through dedicated cell types. Local conditions shape which forms succeed, while single-celled life can remain viable and diverse.

Simulated world

The world contains purple gas bubbles inspired by hydrothermal vents, white dead cells inspired by marine snow, colorful living cells reflecting the diversity of unicellular organisms, and grey rocks. Individual cells and organelles are simulated, with the world running on the video card; a mid-range graphics card can simulate hundreds of thousands of cells.

Evolving over time

Evolution can take a long time, so the game supports Steam Workshop items that can contain sequences of savefiles, not just single saves. Using the in-game savefile list, you can step through evolutionary time by weeks with one click.

A free demo is available to test whether the simulation works on your machine. It is limited to the smallest world size and does not include DNA editing or Steam Workshop access.