Feature 1: Absolute win

Four chessmen are connected horizontally, vertically or diagonally as shown in Figure 5: (a, 1)-(b, 2)-(c, 3)-(d, 4).

Feature 2: Three connected chessmen

Three chessmen are connected horizontally, vertically or diagonally as shown in Figure 5: (c, 2)-(d, 2)-(e, 2) or (c, 1)-(d, 2)-(f, 4).

Feature 3: Two connected chessmen

Two chessmen are connected horizontally, vertically or diagonally as shown in Figure 5: (b, 1)-(c, 1).

Feature 4: Single chessman

A chessman that is not connected to another same chessman horizontally, vertically or diagonally as shown in Figure 5: (d, 1).