Hi, Thanks for playing !! Yes, you are right, the third piece is a little hard to find and I include a hint for it in the next update :)
Glad the game left you with question. I intended the game to raise more questions that it can answer, but that's because I wanted the players themselves to answer them. There are a lot of possible explanations for the end and they are all correct. Even you may think of some explanation I that hadn't thought of.