Chess Variants/Marseillais Chess

Introduction
Marseillais Chess is probably the most notable variant which allows players to move twice per turn.

History
The rules of Marseilles chess were first published in 1925 in Le Soleil, a magazine published in Marseilles, France, from where the variant gets its name. The variant became quite popular in the late 1930s, with players such as Alexander Alekhine, Richard Réti, Eugene Znosko-Borovsky, and André Chéron playing it.

Rules
As already stated, in Marsellies chess each player moves twice per turn. They may move one piece twice, or two pieces once. Castling is considered one move.

If a player gives check on the first move of their turn, their second move is skipped so that the opponent can deal with the threat. A player must move out of check on the first move of their turn, before doing anything else with their second move. It is forbidden to use the two moves to move one's king through check.

En passant captures are allowed even if the opponent moved the pawn with the first move of their turn. However, the capture must be done on the first turn of the move. If two pawns can be captured en passant, both can be captured on one's turn.

Sub-variants

 * Balanced Marseillais chess: White only makes one move on their first turn.