Should trees be blue? Do alien plants move around? Do big pink alien creatures eat rocks? Customize units and modify terrain to create your alien world. You decide what each unit does, how they interact with each other, and what every single part of the world should look like.

Pick from a range of alien plant and animal models. You decide their properties such as size, color, move speed, what they eat, habitat, lifespan, breeding, when they sleep etc. Every property is available to every unit, so you can make them behave as normal or weird as you'd like.

Should your world have lots of small islands, tall mountains, a large deep ocean or maybe something else? You can modify every single part of the terrain to make it your own.

Use your imagination to create biomes any way you want. Make them as big or small, as normal or weird, as full or empty as you see fit. Watch the units that you've created interact with each other as they move, eat, sleep, swim, grow, and breed. Keep experimenting with different combinations to see what happens, then modify them again and again.