I shouldn't be the one to complain about opaque mechanics considering I couldn't explain mechanics in my own game, but I'm too dumb to understand whats going on here.
Viewing post in The Great Banyan Tree jam comments
The basic concept is that you have to plant saplings. To buy saplings, you need leaf currency (which regenerate over time). Once the sapling is planted, you have to give it ample sunlight and water. To water a plant, simply right click it. Once a sapling is grown into tree, you can start merging them to create a small forest, then 2 small forest into a large forest. The progression sometimes can be a bit slow. Hope this clears it up.