The ornamental design for board for board game, as shown and described.
1. Board for board game
1.1 : Front
1.2 : Back
1.3 : Right
1.4 : Left
1.5 : Top
1.6 : Bottom
1.7 : State in use
The broken line showing of the sides and bottom of the design and string, as disclosed in FIG. 1.7, is included for the purpose of illustrating portions of the “article” and forms no part of the claimed design.