Open Game

1...e5 is the Open game (or the Double King's Pawn game). It is Black's classical response to 1. e4. By mirroring White's move, Black grabs an equal share of the centre and scope to develop some pieces. 1...e5 is also one of the few moves that directly interferes with White's ideal plan of playing d4.

But, the move's merit is also a drawback: the longer the position remains symmetrical, the longer White will have an advantage by moving first. Though the move is still common at every level, it saw a modest decline in popularity during the 20th century.

Black's pawn on e5 is undefended, so it is easy for White to develop in a way that restricts Black's possible responses by threatening to capture it. This is White's most common plan, but they may also chose to develop without attacking.

White may attack Black's undefended e5 pawn. By attacking, White keeps the initiative: Black is forced to react to White's plans or they could lose the pawn.

2. Nf3 is the overwhelmingly popular move here, about ten times more common than everything else combined. This attacks the pawn while also developing a piece. Additionally, it controls the d4 square, ready to support a future d4 pawn push, and starts to make room for White to castle. By far Black's most common response is 2...Nc6, to defend the pawn while developing a piece.

Alternatively, White can attack with a pawn.

2. f4, the King's gambit, confronts the e5 pawn and tries to lever open the f-file for an attack on Black's weak f7 pawn. This is the quintessential Romantic chess opening, popular with the likes of Paul Morphy and a staple of chess repertoires in the time when it was considered bad manners to decline a gambit. Its popularity began to wane in the late 19th century, but received some revival in the 20th century thanks players including David Bronstein. A prepared Black player should be able to grab the proffered pawn and keep it.

2. d4, the centre game, smashes the centre open. White can then sacrifice a pawn or two to develop pieces with great speed (2...exd4 3. c3, the Danish gambit).

Since White's pieces are not under threat, they have the opportunity to choose which piece to develop. The main alternatives are 2. Bc4, the Bishop's opening, and 2. Nc3, the Vienna game. These don't immediately challenge e5 so Black has a little more flexibility in how they respond, but they are still solid moves and they keep open the option of either d4 or f4.

Instead of their kingside knight, White can prioritise their queenside knight with 2. Nc3. Depending on Black's response and their preference, they may following with 3. f4 (the Vienna gambit, a souped-up King's gambit).

If White would like to develop their bishop first, then its best move is 2. Bc4 (Be2 is very passive, Bd3 blocks in White's d pawn, Bb5 gets kicked by c6, and Ba6 bxa6, of course). The Bishop's opening is very transpositional depending on how Black responds.

There are many alternative moves, but all with drawbacks. Some of these are playing for tricks:

2. Qh5, called the Wayward Queen or Parham attack, and 2. Qf3 (called the Napoleon attack). White hopes Black will blunder in the face of unbridled aggression and allow them to "Scholar's Mate" them or drop materiel, and if it is Black's first day playing chess, they will succeed (e.g. 1. e4 e5 2. Qh5 g6?? 3. Qxe5+ Ne7 4. Qxh8). If Black keeps their head, these moves are not dangerous.

Some other moves are minor mistakes, where White is just a bit too passive and fails to develop:

• 2. d3?!, the Leonardis variation. A needlessly passive reply where White doesn't develop a piece and blocks in their bishop voluntarily. It resembles a Philidor defence in reverse.
• 2. c3?!, the MacLeod attack aka centre pawn opening. White prepares to push d4, then after exd4 cxd4 they end up with two pawns in the centre. However, this seldom works out as Black can play d5 first.
• 2. a3, 2. a4, and 2. h3 essentially function to pass the turn to Black with minimum disruption to White.

Everything else is very bad. Some of these still have names (there is a lesson here: just because it has a name does not mean it's any good):

• 2. Bb5?, the so-called Portuguese opening. Unlike 1. e4 e5 2. Nf3 Nc6 3. Bb5, the bishop on b5 has nothing to do and can be kicked away by c6. We can only assume it is so named as a play on the Spanish game (i.e. Portuguese is a language that is superficially similar to Spanish).
• 2. Ne2?, Alapin's opening. The knight is misplaced here, preventing development of the bishop and queen. Perhaps White thinks to support either d4 or f4, but it is simply too slow and hands Black the initiative.
• 2. Ke2?, aka the Bongcloud, a deliberately bad "meme" opening used as a joke. An internet-famous game between Magnus Carlsen and Hikaru Nakamura drew by repetition after both players played Ke2 Ke7 Ke1 Ke8 repeatedly.^[1]

Approximate chances

White win 51%, Draw ??%, Black win 45%.

Estimated next move popularity

Nf3 82%, Bc4 5%, Nc3 4%, f4 4%, d4 2%, all others less than 1%

For explanation of theory tables, see theory table and for notation, see algebraic notation.

1. e4 e5

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Wikipedia has related information at Open Game.

Bibliography

• Kasparov, Garry, & Keene, Raymond 1989 Batsford chess openings 2. ISBN 0-8050-3409-9.

• Modern Chess Openings: MCO-14. 1999. Nick de Firmian, Walter Korn. ISBN 0-8129-3084-3.

• Nunn's Chess Openings. 1999. John Nunn (Editor), Graham Burgess, John Emms, Joe Gallagher. ISBN 1-8574-4221-0.

• Panov, Vasily (1973). Teoría de Aperturas, Tomo I: Aperturas Abiertas - Aperturas Semiabiertas. ISBN 84-270-0132-0.
• Schiller, Eric (2002). Standard Chess Openings. ISBN 1-58042-048-6.

• 365Chess: 1. e4 e5

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