Darwinia is a Virtual Themepark game, populated by a sentient evolving life form called the Darwinians.
You can use Engineers to reprogram Control Towers, enabling you to use the building that the Control Tower is connected to. Whenever a creature dies in Darwinia, be it a Darwinian or an evil Virus, it will leave a Soul behind. You may use Engineers to gather these Souls and take them to the nearest Incubator, where they will be reborn into Darwinians.