Three original Four in a Row puzzles illustrate different threats. Each light/dark position comes from a legal alternating move sequence. Diagram rows count up from the base; columns a through g run from left to right.
In this guide
Puzzle 1: two ends of a bottom-row line
Light: c1, d1, e1. Dark: a1, g1. Dark is to move. Which two winning columns does Light have? Can one ordinary block save Dark?
Position as text
Light: c1, d1, e1. Dark: a1, g1. To move: Dark. Rows count upwards from the base.
Show hint
Both empty ends are reachable without additional support.
Answer and explanation
Light wins at b1 or f1. Dark can occupy only one and has no immediate win of its own. After any non-winning dark move, at least one light completion remains legal.
Puzzle 2: what does d1 unlock?
Light: a1, c1, g1, g2. Dark: b1, a2, b2, c2. Light is considering d1. Find Dark’s immediate winning reply and its line.
Position as text
Light: g2, a1, c1, g1. Dark: a2, b2, c2, b1. To move: Light. Rows count upwards from the base.
Show hint
After d1, recalculate the next landing cell in that column.
Answer and explanation
Dark drops in column d and lands at d2, completing a2–b2–c2–d2. Before Light’s move, d2 was unreachable. Light supplies the missing support by playing d1.
Puzzle 3: finish a diagonal
Light has a1, b2 and c3 among its discs. Dark already fills d1, d2 and d3. Light is to move. Which column ends the game? First determine its actual landing square.
Position as text
Light: c3, b2, e2, a1, e1, f1. Dark: d3, c2, d2, b1, c1, d1. To move: Light. Rows count upwards from the base.
Show hint
The opponent’s three-disc stack also supports your finishing move.
Answer and explanation
Light drops in column d, lands at d4 and connects a1–b2–c3–d4. Dark supporting discs do not prevent the win. Light wins immediately; Dark gets no subsequent blocking move.
How to replay the studies
The first two studies can be recreated in a short two-player session on one device. Start a fresh local round and use the text below the diagram. A diagram is not an automatically loadable save. After every move, discuss not only the disc’s side but the next landing cell it creates above.