What is an actual Biome, though? How does what brick I choose determine what environment they go in.
Go to biome options by hitting the biome option. The small squares at the bottom are the main thing you're worried about. The 9 bigger squares above that allow you to choose what special bricks you want to spawn in each biome, and what color/print you want them to have.
For example, the first biome is the default biome I think, it mostly has just hills. So if you made one of those squares a green pine tree brick, then green pine trees will spawn in that biome.
Anyways, this looks awesome so far! Can't wait for future updates