warning: it is helpful to know chess notation and some chess terminology before engaging this write-up.
The grob is a very unusual chess opening which starts with white moving the king's knight pawn two squares. Often, it is thought to be the worst opening, but really it is just the most misunderstood opening. The strategy behind the grob varies depending on black's response, but is generally used to gain space on the kingside. A well booked advocate of the grob should have an easy game over someone who has not studied the complex positions that arise from its use. The grob will most often lead to unclear positions. This pretty much means that each player's chances of winning are equally bad.
The Tactical Grob
The tactical grob is the most common variation of the grob. White gambits a pawn and instantly attacks blacks queenside.
White is trying to undermine the b7 square.
How ever black defends, he will have to give back a pawn. Possible continuations are...
Attacking d5 and b7. White will have a strong center which allows him a better endgame.
White is simply up a piece.
The Spike is black's most accurate method of play. Black establishes a strong center making things a little difficult for white.
The main moves here are either 3...Nc6 or 3...c6
The Basman method of play (4.d3) is sometimes seen, but black has easier play against white. Also possible is 4.c4 Be6!
White has built up strong counter play in the center. Now, he is weakening black's flanks.
Bxc6+ is worth considering as it leaves black with a ridiculous pawn structure.
Black is activating his pieces, but both players have equal chances.
The Critical Line
Black counters white's kingside thrust. It's kind of a positional trap.
Black is moving his queen a lot, but he has more than adequate compensation for the tempos.
The grob is an exceptional opening both positionally and psychologically. It has been employed by strong players such as Michael Basman, Skembris (the number one Greek player), and Savielly Tartakower. Tartakower describes the psychological effect this opening could have on chess players. When someone plays an outrageous first move, they feel obligated to win the game. Overconfidence and alarm could cause him to take risks that lose the game. Basman, on the other hand, finds great positional value in the opening. He uses the strong pawn structure and open lines provided by the grob to win his games rather than rely on the condition of his opponent. Skembris' fantastic handling of the opening supports Basman's beliefs.
Despite the unusual look of the grob, it is a fabulous opening. It has no refutation, nor does it force a win, but it gives white many resources to succeed in his game. As long as the grob remains dubious, it will be playable.