Corner Claim

Setup

Two players share a 14×14 board; three or four players share a larger 20×20 board. The bigger board is only used when there are enough people to fill it — two players on twenty squares a side barely meet, and the game becomes a long solitaire rather than a contest.

Every player holds the same twenty-one shapes: one single square, one pair, two shapes of three squares, five of four, and twelve of five. That is every distinct shape you can build from one to five squares, counting a shape and its mirror image as the same piece.

Each player has a starting square. At four players it is one of the four corners of the board; at two players the two starting squares sit inside the board rather than in its corners, so that the two colours run into each other early.

Nothing is hidden. Every piece every player still holds is shown throughout, and so is the whole board — there is no luck in this game at all and nothing to discover.

Play begins with the first seat and passes round the table in order.

How to play

On your turn you lay exactly one of your remaining shapes on empty squares of the board. You may turn it and you may flip it over; a shape and its mirror image are the same piece, so both are always available to you.

Your first piece must cover your own starting square. Anywhere else is illegal, however good it looks.

Every piece after the first must touch at least one of your own pieces at a CORNER — diagonally, point to point.

And no piece may ever share an EDGE with another of your own pieces. Corner yes, side no. That one pair of rules is the whole game: your colour spreads across the board as a chain of diagonal contacts and can never grow into a solid block.

Pieces of other colours are not your problem. You may lay a piece flush against an opponent's along a whole edge, and they may do the same to you. Another colour blocks you only by occupying a square you wanted.

If you have no legal placement left you pass, and the other players carry on without you. You cannot pass while a placement exists — running out of room is the endgame, and skipping a turn would sidestep it.

The game ends when nobody can place anything. That usually happens with several pieces still in every hand.

Controls

Your remaining shapes sit in a tray below the board. Tap one to pick it up; it lifts and the board shows you where it can go.

The board marks your open corners — the squares you are entitled to build from — so you can see at a glance where your colour is still alive.

Rotate and flip buttons turn the piece in your hand. Shapes that look the same however you turn them, like the square and the plus, do not offer the buttons.

Drag the piece across the board to position it. A legal placement lights up in your colour; an illegal one shows red, so you can feel out where a shape fits without guessing.

Lift your finger, or tap Place, to lay it. Tap the piece in the tray again to put it back and choose a different one.

When nothing you hold fits anywhere, you are out of the game's moves: your turn is skipped automatically from then on, so you never have to pass by hand. A Pass button exists for that moment and stays disabled while any placement exists, so it can never cost you a turn by accident.

Scoring

You are scored on what you did NOT manage to place. Every square still sitting in your hand at the end costs you one point, so a five-square shape left over costs five and the single square costs one.

Place all twenty-one of your shapes and you score 15 instead of a penalty — a large swing, and worth playing for once you can see the end coming.

Place all twenty-one and finish on the single square and you score a further 5, for 20. Holding the smallest piece back for last is a real plan and not a trick.

The highest score wins. Because almost everybody finishes with something left, most games are decided in negatives — minus eight beats minus fifteen.

Winning a match awards 22 points, a draw 8 and a loss 3. Two-player games move your rating; three- and four-player games award points and stats but leave the ladder alone, as every non-duel does.

Winning

The player with the highest score when nobody can move takes the game.

If two or more players tie on the highest score, the game is a draw between them.

There is no early win. Nobody is eliminated and nobody is knocked out — a player who runs out of room simply stops placing while everyone else carries on.

In a three- or four-player game somebody leaving does not end it. Their squares stay on the board, they stop placing, and the rest of the table plays on to a real finish — and a player who left cannot win, however their score stands: the best score among the players still at the table takes it.

Tips

Spend your big shapes first. Every square is a point, and the five-square shapes are the hardest to fit once the board tightens — being left holding three of them at the end is how most games are lost.

Head for the middle. A piece laid against a wall has fewer corners pointing into open board, and the opening is entirely about growing.

Count your corners, not your squares. The number of open corners you own is how many futures you still have; a move that lays four squares and opens one corner is usually worse than one that lays four and opens three.

Corners are also the thing to take away. Laying a piece so that it covers the square an opponent was going to grow through costs them far more than the squares it costs you.

Keep the single square and the small shapes for the endgame. They fit into gaps nothing else will reach, and the last few turns are entirely about gaps.

Push into a gap early rather than late. A one-square-wide channel into open board is worth more than a comfortable placement in your own territory, because once somebody else closes the mouth of it the whole area is gone.