Once the basic Hedgehog structure is in place, and depending on how White responds, Black has various ways of reorganizing their pieces.
There are also situations where Black can create a kingside attack, by playing ...Kh8, ...Rg8, and ...g5, often followed by doubling rooks on the g-file and pushing the g-pawn to g4.
In the early 1970s, "'hedgehog' was a generic term for any setup that was cramped, defensive and difficult to attack", but today refers specifically to this formation.
[1] The Hedgehog first became extensively analysed in the 1970s, when players began to appreciate the rich variety of strategic ideas that arose from it.
Fischer's crushing victory in this game, in which the Kh1/Rg1/g4 method of attack was vividly demonstrated, so impressed Andersson that he later became one of the foremost Hedgehog exponents himself,[2] for example Karpov–Andersson, Milan 1975.