Stages of the Game

A chess game can be divided into three parts: the opening, the middlegame, and the endgame.

The opening

The initial moves of a game are referred to as the opening. Its goal is to achieve good piece development to control the board and get a favorable position that could provide an advantage later in the game.

The most common openings have specific names, and there are more than 1327 recognized openings. Some of the most popular ones are the Ruy López, the Italian Opening, the Sicilian Defense, and the Queen’s Gambit.

Openings are not a single sequence of moves, each one has many variations and different moves from which to choose. These are called variants or lines, and they make the first moves much more varied and interesting.

They can be classified into six types:

Open games start with 1. e4 e5 and often lead to positions with many tactical moves and open lines.
Closed games occur after 1. d4 d5. These typically lead to slower positions where players try to gain a long-term advantage.
Semi-open games start with 1. e4, but Black does not respond with e5, instead, they make other moves that lead to openings such as the Sicilian, French, or Scandinavian defenses.
Semi-closed games are similar to semi-open games, but instead of 1. e4, White plays 1. d4, leading to openings like the Dutch Defense.
Indian defenses begin with 1. d4 Nf6. They typically follow the strategy of controlling the center with pieces and attacking the opponent’s advanced pawns. Some examples are the King's Indian Defense and the Nimzo-Indian Defense.
Flank openings start with a pawn move from the c or f file (flank pawns) by White, such as the English Opening and the Bird Opening.

Generally, the strategies have the same strategic objectives, which are:

The development of pieces to place the knights and bishops on squares that are more useful for gaining an advantage over the opponent.
Controlling the center gives an advantage over the board, as there’s more freedom of movement for the pieces and limits the opponent’s moves.
Ensuring the king's safety is crucial, so castling should be done on time to keep the king safe from danger.
A good pawn structure is key to a strong position. Pawns advance to give space to other pieces, and openings aim to avoid creating weaknesses in their own pawn chains while creating them in the opponent’s.

The middle game

After the opening comes the middle game. This is the phase where most or all pieces have been developed (moved from their starting positions), and players begin to form attack and defense plans based on the board’s position.

Each opening leads to a different position, so key elements like pawn structure can lead to different strategic moves depending on the position of the pieces, or the creation of defensive structures, etc. All of this depends on the player’s goals and piece positioning.

Throughout the game, chess players analyze the position to find the best moves, but it is especially important to analyze the position during the middlegame to know whether it’s time to exchange pieces and transition into an endgame, or if a sacrifice is worth the advantage, or whether it’s better to attack or defend a piece.

A small material advantage can turn into a victory later in the endgame, but it is important not to get carried away because just as you can gain an advantage, the opponent can do so as well. Things can change quickly in the middle game.

At some point, pieces are captured and the position simplifies. This leads to the third and final stage of the game: the endgame.

The endgame

The endgame, as its name suggests, is the final phase of the game.

This phase is distinct from the others because there are far fewer pieces left, and strategies change.
Pawns become very important in the endgame, and most of the time, the main goal of players is to promote pawns to a queen or a rook, and in rare cases, to a knight or bishop.

The king becomes a very important piece in the endgame, primarily for attacking. Unlike in the middlegame, where the king must remain protected to avoid checkmate, in the endgame, the king becomes active and usually moves to the center to protect its pawns and attack the opponent’s.

In the endgame, situations of Zugzwang can occur. Zugzwang is a disadvantageous situation where any move the player makes will result in a loss. It’s like a death sentence, any move will mean defeat. This is more common in the endgame but can also happen in the other stages, though it’s rarer.
Depending on the type of pieces left on the board, the endgame can be classified into three types:

Basic mates are positions where one player has one or two pieces, and the other has only a king, making it easy to checkmate.
King and pawn endgames have no major pieces, and the goal is to promote pawns to checkmate.
There are also more complex endgames, depending on the pieces remaining, such as "rook vs rook and pawn," or "knight and bishop vs rook," etc.

Not all games reach the endgame, they can end in the middlegame or even in the opening. It is not guaranteed that all three phases will occur in a game.

There also doesn’t have to be a winner or a loser. A game can also end in a draw.

Game results

Games can end with the defeat of one of the players or a draw.

Players can lose for three reasons:

The first one is checkmate. If one player checkmates the other, the game ends, and the player who gave the checkmate is declared the winner.

If a player runs out of time, they lose automatically. Not all games have a clock, but competitive games always use a timer, whether it's one minute or several hours.

One player may resign, conceding the victory to the opponent. This may happen for various reasons, such as a bad move or a difficult position, but regardless of the reason, when one player resigns, the game ends, and the winner is determined.

If there’s a draw, no player wins or loses; the game is simply null, and no one wins.

Stalemate occurs when the player who is to move cannot make a legal move. They cannot move the king because it would result in a check, nor can they move any other pieces, either because they don’t have any or because they are blocked. It's important to note that in stalemate, the king is not in check, it's simply that no moves can be made to continue the game without breaking the rules.

Perpetual check happens when one player can continuously give a check, but not checkmate. A sequence of moves can continue infinitely without either side winning, so it’s declared a draw.

Insufficient material for checkmate occurs when neither side has enough pieces to checkmate. Typically, this occurs when only the kings remain, or one side has only a King with a knight, or a bishop.

Mutual agreement occurs when one player makes a move and offers a draw to the other. The other player can either accept or reject the offer. If accepted, the game ends, if rejected, the game continues.

Repetition of position happens when the same position is repeated three times during the game.