The 2nd part of the Reus tutorial is entitled Second Era. This takes the basic tera-forming skills of your 3 giants and expands them to the next level. Once earned, their secondary abilities can improve tiles, much in the way a worker unit does in Civilization.
“Reus is an indie god game developed by Abbey Games. The game is inspired by other god games like Populous, Civilization and Black & White but also by other games like The Binding of Isaac. The game allows players to take up the role of mother nature on a planet and create a utopia for humanity that settles on the planet.”
Link to Abbey Games info, including their monetization policy.