Balbo's game

Balbo's game is a chess variant invented by M. G. Balbo in 1974. The chessboard has a novel shape comprising 70 squares, and each player commands a full chess army minus one pawn.
The game was featured in Le Courrier des Echecs magazine, September 1974.

Game rules

The starting setup is as shown. All the rules of chess apply, except there is no castling, and promotion squares are specially defined:

At the end of the d- through h-files, pawns have normal promotion options.
At the end of the c- and i-files, pawns may promote only to a bishop or knight.
At the end of the outer four files, pawns may not promote.