Brian's example

gistfile1.sql

CREATE TABLE games (id int);
CREATE TABLE scores (game_id int, player_name VARCHAR(255));

INSERT INTO games(id) VALUES (1);
INSERT INTO games(id) VALUES (2);
INSERT INTO games(id) VALUES (3);

INSERT INTO scores(game_id, player_name) VALUES (1, "dj");
INSERT INTO scores(game_id, player_name) VALUES (1, "brian");
INSERT INTO scores(game_id, player_name) VALUES (1, "daniel");

INSERT INTO scores(game_id, player_name) VALUES (2, "daniel");
INSERT INTO scores(game_id, player_name) VALUES (2, "dj");

INSERT INTO scores(game_id, player_name) VALUES (3, "dj");
INSERT INTO scores(game_id, player_name) VALUES (3, "brian");

SELECT games.* FROM
    (SELECT game_id FROM scores WHERE player_name = "dj") s1
  INNER JOIN
    (SELECT game_id FROM scores WHERE player_name = "daniel") s2
      ON s1.game_id = s2.game_id
  INNER JOIN games
    ON games.id = s1.game_id;
-- => 1, 2

SELECT games.* FROM
    (SELECT game_id FROM scores WHERE player_name = "dj") s1
  INNER JOIN
    (SELECT game_id FROM scores WHERE player_name = "brian") s2
      ON s1.game_id = s2.game_id
  INNER JOIN games
    ON games.id = s1.game_id;
-- => 1, 3