Koshin StudioNegaeri Shogi
Sandwiched pieces defect to your side.
Defected pieces get promoted.
Free. Runs in your browser, no install or sign-up. The game is available in English and Japanese.
What it is
A small 6×6 board and shogi pieces, played like Reversi: drop a piece from your hand so that it sandwiches your opponent’s pieces in a line, and the sandwiched pieces flip to your side. Every piece that flips is also promoted (pawn to tokin, rook to dragon, bishop to horse). A promoted piece moves in new ways, so it can create new sandwiches, and the flips chain. A single move can change the whole board.
Rules in short
- Four kinds of pieces: king, pawn, rook and bishop. They move as in shogi.
- On your turn you either drop a piece from your hand (this is when sandwiching happens) or move a piece on the board (no flipping).
- Sandwiching works in all 8 directions. The edge of the board also counts as an end, so pieces pushed against the edge can flip together.
- Kings never flip. Pieces next to your own king do not flip either, so the squares around the king are safe.
- Capture the opponent’s king to win. If neither side can move, the player with more pieces wins.
- Online games have 3 minutes per player, plus 5 seconds per move.
Ways to play
- Two players on one device.
- Against the AI at three levels (weak, medium, strong). The AI runs in your browser.
- Online against another player, with an Elo-style rating and a ranking. A name is stored, and no sign-up is needed.
About the balance
The numbers (how many pieces each side holds, the king’s protection) were tuned by AI self-play. Balance in human-versus-human games has not been verified yet. If one side feels too strong, please tell me.
This is the English version of the Japanese page. Online play stores your name, rating and results (see the privacy page, in Japanese).