In the semi-open games White plays 1.e4 and Black breaks symmetry
immediately by replying with a move other than 1...e5. The most popular
Black defense to 1.e4 is the Sicilian (1...c5), but the French (1...e6, normally followed by 2.d4 d5)
The Sicilian and French Defenses lead to unbalanced positions that
can offer exciting play with both sides having chances to win. The
Caro-Kann Defense is solid as Black intends to use his c-pawn to
support his center (1.e4 c6 2.d4 d5). Alekhine's, the Pirc and the
Modern are hypermodern openings in which Black tempts White to build a large center with the goal of attacking it with pieces.
Other semi-open games have been studied but are less common; see Semi-Open Game for details.