Dots Connect

Players take turns drawing one line between two neighbouring dots. Whoever draws the fourth side of a box claims it and immediately plays again, so a single move can cascade through a whole row. When every line is drawn, the most boxes wins.

Once the safe lines run out, every move hands something over. The player forced to open the first long chain usually loses it — which is why strong play often means declining the last two boxes of a chain to keep the move, rather than taking everything on offer. The Ruthless opponent does exactly this, and solves the endgame outright once few enough lines remain.