The Sapling

While the simulation in this game can be deep and complex, it's introduced to the player step by step; it never becomes overwhelming. Each scenario tasks you to build an ecosystem that meets specific requirements, and introduces a small number of new concepts. The sandbox offers the same functionality as the scenarios (but, obviously, with everything unlocked), but also much more: play with the procedural planet generator to get the exact planet you want, whether it's a desert world, an underwater world, or whatever you come up with. It even allows you to define up to 8 seasons to spice that ecosystem up a little. While playing, you can continue to change things: the next ice age is always only a few clicks away.  The Forest