okkaystudio
Reversi lessons · Basics · Step 3
Watch Out for X- and C-Squares
The square diagonally next to a corner is the X-square, and the edge squares right beside a corner are C-squares. Playing there while the corner is still empty makes it easy for your opponent to take that corner. In the opening and midgame, look first for moves that don't give your opponent a corner.
Puzzle 1
Which move doesn't give White a corner? (Black to move)
Show answer and explanation
The yellow circle marks the answer. The other two moves are the X-square and C-square next to a corner, so White takes the corner right away. One of them also flips the most discs, which makes it an even trickier trap.
Puzzle 2
Of the three legal moves, pick the safe one. (Black to move)
Show answer and explanation
The yellow circle marks the answer. The C-square and X-square next to the corner open it up for White. The square away from the corner is safe.