It means that the coin has lost approximately half of its initial value. Polybius was 10 times cheaper on the exchanges after the ICO. Most probably you are going to see this in the majority of new ICOs because of the falling BTC.
I also have the same question as the OP, does it mean the rest of the coins are kept by the Exchange?
Does market cap means total value of the coin? Not the amount of coin itself? Because all this time I thought market cap is the total coin at the market.
Wow.
It looks like both you and the OP should probably learn more about crypto and market based trading in general prior to investing in any of it. You're bound to lose a great deal of money with this kind of ignorance.
Please, for your sake, do a few days or weeks of research (at least) before investing any(more) of your hard earned money.