Game 5221276
To be fair it isn't a 4 way fork, one pawn protected by a pawn, one bishop covered by rook. The rook move to e7 saves all pieces unless you felt like a trade of knight for bishop. Yes in theory your knight could take any one of the 4 pieces but you never would.
A true fork is where a knight moves to a position where is in a position to take an opponents piece either without loss or say forking 2 rooks only 1 can escape but you still take the other as its value is greater than your knights therefore a good fork.
As mentioned you get a fork of 2 pieces - simple fork, fork of 3 pieces - triple fork, fork with check - king plus other piece, royal fork - king & queen, triple royal fork - king, queen & another piece. That said a lot of folk only count a royal fork as king, queen, & third piece.