Eight by eight, and a tiny crossroad in the middle.
Every game starts with the same four discs in the centre — diagonally arranged so each
colour mirrors the other. Dark moves first, and from here on every placement must
flank
an opponent's disc. We'll see what that means next.
Dark · 2
Light · 2
The starting position. Dark plays first.
Section 02 · A legal move
A move must sandwich at least one opposing disc.
Place your disc on an empty square so that, in some straight line — horizontal, vertical,
or diagonal — your new disc and an existing disc of yours bracket an unbroken run of the
opponent's discs. From the opening, Dark has exactly four legal moves. Click any glowing dot.
Click a glowing square
Each one flanks the Light disc between it and a Dark disc already on the board.
Section 03 · The flip
Every flanked disc flips to your colour.
After your placement, every opposing disc you sandwiched — across all directions at once —
flips to your colour. A single placement can flip discs in multiple directions in the same turn.
Watch this dramatic flip:
Dark places at the highlighted square — three Light discs flip in two directions.
Section 04 · Eight directions
Lines run in every direction from your disc.
Flanking is checked along all eight rays — N, NE, E, SE, S, SW, W, NW. A single move can
flip discs in several directions simultaneously, but only the rays that are properly
sandwiched count. A run interrupted by an empty square doesn't flip.
Dark plays at the centre. Three rays sandwich Light discs; the others don't.
Section 05 · Turn flow
A turn, in order.
Reversi turns are short — one disc per turn, no exceptions. The pass rule is the only twist.
①
Find any move that flanks an opponent.
If you have one, you must play it — passing isn't optional when you have a move.
②
Place your disc.
Empty square, your colour up.
③
Flip every flanked disc.
All directions, all opposing runs that are now bracketed.
④
No legal move? You must pass.
If neither side can play, the game ends — even with squares empty.
Section 06 · Legal vs. illegal
What flanks — and what doesn't.
These tiny boards show common new-player mistakes side-by-side with valid plays.
Legal flanks
Horizontal sandwich — places Dark, flips one Light.
Diagonal sandwich — long runs flip too, as long as they're unbroken.
Not allowed
No flank — the new disc isn't bracketing anything.
Empty square in the line — a gap breaks the sandwich.
Placing on an occupied square — never legal.
Section 07 · Winning
Most discs of your colour wins.
The game ends when neither player has a legal move — usually after the board fills. Count
discs: whichever colour has more wins. Tie counts are draws. A few strategic notes most beginners
miss:
★
Don't grab the most discs early.
Mid-game position matters far more than current disc count.
★
Corners are gold.
A corner disc can never be flipped — it's permanent.
★
Avoid the X-squares.
The squares diagonally adjacent to corners often hand the corner to your opponent.
Section 08 · Try it
Now play a quick game.
A live solo demo against an AI opponent. Place your discs, watch the flips, and see if you can
out-flank the bot.