We finally have some information and proofs about Emercoin, Hashflare, Polybius and Hashcoin affiliation and dubious practices.

First, Hashflare for some time accepted only one cryptocurrency besides Bitcoin — Emercoin and that is already suspicious. They have not accepted more popular currencies like Zcash, Ethereum, Litecoin, etc.

Second, Hashflare has changed the terms several times already, first by limiting all "lifelong" SHA-256 (Bitcoin) contracts to 1 year in August 2017 and then by changing the BTC minimum withdrawal amount to 0.05 BTC, effectively locking the funds of everyone who invested relatively small amounts of money. Also, the withdrawal fee was raised to 0.0007 BTC, but actual withdrawal fees that Hashflare pays can be seen in blockchain and it is significantly less than that amount.
That suggests lack of liquidity, they do not have the money to pay back and they are inventing the way to lock most of the money.

Comparing the companies information on the websites, you can see that the same people own Hashflare, Emercoin, and Polybius. The main company is called Hashcoins.

Hashflare looks like a classic Ponzi scheme and, most probably, they do not have sufficient mining equipment to actually mine on all the contracts they have sold. Also, they have referral scheme that isn’t even trying to disguise itself as non-Ponzi. They will give you some instant kickback if you will refer other people and they will invest in Hashflare.
Hashflare has even offered cashback via Letyshops cashback service! Now this cashback scheme is suspended, but you can still see Hashflare on the Letyshop website: https://letyshops.com/shops/hashflare
This shows that Hashflare is really desperate for cash right now.

Polybius should be a second Ponzi scheme under a different name, they also accept Emercoin as payment, besides BTC, ETH, and USDT.

How have they managed to keep this truth hidden for so long?

They have printed their own money to fuel the Ponzi!

If you can make your own money — Emercoin — you can run the Ponzi for a really long time, without any real mining equipment and investments.

And while Emercoin team claims that Emercoin is a perfect currency for some services like DNS, SSL and other trusted storage, it was mostly used to fuel Hashflare and Polybius.

The legitimate uses for Emercoin would never get even the tenth of the same trading volume.

So, the Emercoin price rise was in turn fueled by these Ponzi schemes.

The truth has already started to leak out, you can check these sources as well:
https://www.reddit.com/r/hashflare/comments/7l3rll…
https://www.scambitcoin.com/hashflare-io/

Once more people will realize this, they will try to pull their money out of Hashflare and Polybius. Like with any Ponzi scheme, there would be not enough money to pay everyone, Hashflare and Polybius will invent some other excuses for not paying back and will eventually default and take the Emercoin value with them.

My advice is to stay clear of Emercoin, Hashflare, and Polybius and pull all the money out now if you do not want to lose them. There are a lot of reputable cryptocurrencies around, so you can just invest in something honest and useful.