From the problem cellar
Five in a row problems
30 positions in three difficulties. A tick marks the ones you have solved in this browser.
Stones on a 15 × 15 lattice: make five in a line, block every open four.
Easy · #501–510
Two moves: make a four that also creates a second threat.
Medium · #511–520
Three moves of continuous fours. Every stone must force the block.
Hard · #521–530
Four moves of fours in a row. Find the start that keeps every block forced to the end.