I'm back with more history discoveries. After research since the discovery of the Play Coin, I discovered this: a big stone tablet with an inscription. It said: A-1. This means two things: this is made after the end of prehistory, when human could write. It also said: AR. I think it means: Awakening Resources. If so, this might be a holy tablet mankind used to communicate with their nature environment. The inscription below the ? mark says: Nintendo. This must be a god or such. more info below