The Endgame (roughly the last 14 to 20 moves) is a distinct phase. The heuristic approximations of the mid-game (Mobility, Frontiers) are replaced by precise calculation. Because the remaining search space is small, players can often calculate the entire game tree to the end.
1. Counting and The "Sweet 16" Trap
Counting is the process of calculating the exact disc differential. Players visualize move sequences to determine if a line results in +2 discs or -4 discs.
1. Counting and The "Sweet 16" Trap & Trap
The Sweet 16 Trap: In the endgame, a common tactic is to force the opponent to play entirely within the central 4×4 square (Sweet 16) while you control the edges. This forces them to flip discs that you can immediately flip back, often resulting in a "wipeout" or massive score swing.
2. The Stoner Trap
The Stoner Trap is the most famous named tactic in Othello, popularized by John Stoner. It is a specific sequence that forces a corner exchange favorable to the attacker. It challenges the basic rule of "never play an X-square."
2. The Stoner Trap
The Anatomy of the Trap
Phase 1: Diagonal Control The attacker (say, Black) must possess a disc on the diagonal connecting to the target corner (e.g., the H8 corner).
Phase 2: The Bait (The X-Square) Black plays to the X-square (e.g., B7). This seems to give White the A8 corner.
Phase 3: The Attack Black plays a move (e.g., C8) that threatens to take the other corner (H8). White is now forced to defend H8 (usually by playing G8).
Phase 4: The Switch Crucially, White's defensive move at G8 flips the B7 disc (the original X-square play) because Black controlled the diagonal. Now that B7 is White, Black can capture A8 or use the newly flipped disc to gain access to H8.
Outcome: The Stoner Trap forces the opponent to "buy" a corner at the exorbitant price of giving up an entire edge or the opposite corner, usually resulting in a net loss.
3. Swindles and Tezzo
Swindles
A Swindle is a tactical maneuver where a player moves into a "pair" of squares (usually a Corner and its C-square) in a way that prevents the opponent from taking the other half of the pair.
Example: A1 and B1 are empty. Black plays A1 (Corner). Normally, White would wedge at B1. But if Black's move to A1 flips the only disc White could use to access B1, White is locked out. Black then plays B1 on the next turn, securing both.
Move 0 / 0
Start
Example: A clever sacrifice
Tezzo
Tezzo is a Japanese term generally referring to clever, unexpected tactical sequences that reverse the flow of the endgame, often involving parity swaps (forcing the opponent to pass).
4. Parity in the Endgame
As the board fills up, empty squares become divided into isolated regions. The player who plays last in each region generally gains the advantage.
Goal: Try to make your opponent pass. If they pass, the parity of every region flips in your favor. This is why "perfect play" engines like Zebra prioritize parity so heavily in the endgame.