The Hippo, it's a system. I think it's more likely to see it played by black then by white..
The Beginning???
Actually all of white's pieces make some play on the center of the board. The bishop's on the diagonals slash right thru the center. The knight's and the two d and e pawns have presence in the center. They just dont' extend to black's side of the board, but they make it hard for black to pute presence into whit's side of the board.
Recently I played an opponent who had a peculiar openning that did not follow any normal of the normal lines of defense. As a matter of fact this opponent never competed for the center. He simply arranged his pieces
who was it
It's pointless. Literally pointless. I advise using a c5/d5/e5 pawn duo, and play to restrain f4. The point is that e4/c4 can be responded to by d4, when whites next play is f4. d4 is just suicidial, and if white doesn't make contact in the center eventually he will be squeezed to death.
And keep an eye out for threats created by the knights hopping.
Recently I played an opponent who had a peculiar openning that did not follow any normal of the normal lines of defense. As a matter of fact this opponent never competed for the center. He simply arranged his pieces