Corner Control: Step-by-Step Guide

Prerequisites

Know how to list legal moves and count flips for each option.

How to spot the opportunity

• Watch for quiet moves that force your opponent to open a corner.
• Avoid playing next to an empty corner unless you can take it immediately afterward.
• Use “X-square” and “C-square” heuristics: these are often poison unless they flip into a guaranteed corner.

Example forcing line

1. Black plays C4 to squeeze the north-west, leaving White only D3 and C5.
2. After White responds at D3, Black jumps to C3, flipping upward and setting up the corner.
3. If White blocks with B3, the reply A3 hands Black the safe follow-up A4 into the corner.

The goal is to reduce the opponent’s options to the “poison” squares around the corner. Count their legal moves each turn; if they fall to one, you can plan two moves ahead and claim the corner safely.

Why it works

A corner disc can never be flipped. Capturing it anchors the whole edge, shrinking your opponent’s mobility and giving you safe follow-up moves.

Try it now

• Load a new easy game, pause auto-play, and play only moves that reduce the opponent to two replies.
• Record when an X-square becomes safe—note which discs you needed as anchors.
• Finish the sequence by claiming a corner, then evaluate how the connected edge becomes unflippable.

Practice checklist

• Count the parity of remaining moves before committing to a corner race.
• Simulate the opponent’s best reply—ensure they can’t immediately take an adjacent corner.

Board-vision drills

Common pitfalls

• Grabbing a corner early but leaving the opposite corner open on the next move.
• Ignoring tempo—sometimes the right play is to sacrifice a disc to keep the corner sealed.