It's a dead cryptocurreny. I don't recommend investing in Marinecoin at all. Such cryptocurrencies don't make profit in any way. If you want to make a profit join the icos.
It's been revived, so I wouldn't say its dead cryptocurrency. I see it as one of the exciting risk free currencies of 2018. Risk free in the sense that there is an airdrop currently one where you can get 450,000 mtc for free, and all you have to do is to hold it. The only investment you need to make right now is the time needed to qualify for the airdrop