From the rule sheet:

Colorloc is a game for 2 players. Each player has 23 pieces. The pieces are of three types: colored, grey or plain. Each player has 16 colored pieces, 6 grey pieces and 1 plain piece. Whites plain piece is solid white. Blacks plain piece is solid black.

The object of the game is to capture your opponents plain (target) piece.

The basic premise of the game is that a colored piece is locked into lines of it's own color and the black lines. Each piece has it's own special rules to follow in addition to this. Grey pieces can move on any line, and the grey 'dot' pieces are particularly powerful..