CyanDot - not sure about when the game started.... but there is no more middle piece of the submarine - you just get the pin.
A thread in another section says that someone who had the middle section had it taken away and replaced by the pin by VMK
The middle pieces weren't suppose to be released but they accidently did. Then they quickly replaced the prize of the game with the pin but if players already got the pieces they get to keep them. I heard they will be released eventually though so don't spend too much on them.