I really like the concept of two worlds being secretly connected and the player finding out through gameplay. However, I think the game is a little small for what is described. Unless the double-sided planet is a consistent aspect across multiple levels, I would expand this out to a whole solar system of planets to really drive how every action is in one big system. I think the theme could go a little further past just "plant a seed". Maybe the theme could be the butterfly effect or something where one change effects everything. Overall, though, I think that this is a fun idea with a good twist that I would definitely like to play. Just hoping to see more!