AFAIK this site is only temporary, the game isn't running ATM, because he's waiting on his devs to finish the new game/site.
So no worries.
As far as ponzi's are legit, Hellsgremlin has proven the community he is legit and no scammer as he refunded people for an earlier ponzi that ended because of unforseen reasons.
He's only doing that to make sure he's somewhat trusted and some bigger bets come rolling in, after which he'll run, like they all do. If you """invest""" in this, you're not that smart, to be honest...
You obviously didn't follow that thread: he didn't have to, as he transferred his debt to another person. He didn't came through in the end, but HG did.
He could have just taken another username and no one who would know. Instead he chose his tainted one and did his best to regain trust.