Celtic!
Cameron Browne
(c) 2009

Celtic! is a tile placement game in which players strive to complete the best knot.

New: Celtic! World Rankings

Rules

Pieces: The game is played with a set of 25 tiles showing path segments. The first player (Orange) owns the 10 tiles with orange background, the second player (Blue) owns the 10 tiles with blue background, and both players share the 5 neutral tiles with white background.

The 25 tiles.

Start: The neutral tile with the most crossings is placed in the middle of the playing area to start the game.

Starting tile.

Play: Players then take turns adding either a tile of their colour or a neutral tile to extend at least one path end on the main group. Neighbouring tiles do not have to match background colour, but path ends cannot be cut off as shown below.

An illegal move (left) and a legal move (right).

The growing design must fit within an imaginary 5x5 grid at all times, and moves that would let it extend beyond this limit are not allowed. For instance, if a player wished to play at point p in the following example they could not make the move shown in the middle as it would open onto the outside of the imaginary 5x5 window, but they could make the move shown on the right as it keeps the design contained within the 5x5 window.

No move may allow the design to extend beyond an imaginary 5x5 grid.

Players who cannot make a move must pass that turn.

Aim: The game ends when no player can make any more moves, which will typically occur when all paths have been closed to form knots. A knot is simply a closed path with no open ends, i.e. if you follow that path around with your finger you will return to the starting point.

The game is won by the player with the highest knot score, which is given by number of tiles of their colour visited by a single knot.

For example, the following game has been completed to form three interlocking knots. The smallest knot (bottom) visits 2 x blue and 2 x orange tiles, the next knot (middle right) visits 3 x orange and 3 x blue tiles, and the longest knot visits 7 x orange and 9 x blue tiles: Blue has the highest knot score and wins this game.

Blue wins.

If scores are tied then the next highest knot scores are compared, if still tied then the next highest, and so on. If all knots have equal scores then the game is a draw.

Notes

If a player inadvertently makes a move that would let the design extend beyond its 5x5 limit, then that tile is taken back and the player forfeits their turn.

Each player's highest knot score need not necessarily come from the same (longest) knot.

Try to get as many of your tiles in play as possible. Close off path ends to limit future growth if they contain a majority of enemy tiles. Use neutral tiles to interfere with the opponent's best path.

It is unlikely that all tiles will be used in each game. The starting tile does not have to always be the central tile, although it will always be one of the nine central tiles.

The tiles are based on the following five basic shapes. There are 1 x neutral, 2 x orange and 2 x blue of each shape.


The five basic shapes.

Puzzles

Easy Puzzle: Fit all 25 tiles into a 5x5 grid. Here is one solution consisting of three interlocking knots.

Hard Puzzle: Form all 25 tiles into a single 5x5 knot. This is tricky! Email me for a solution.

History

Celtic! tiles and rules copyright (c) Cameron Browne, November 2009.

The name Celtic! comes from "celtic (k)not". Hopefully C programmers will get this joke.


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Site designed by Cameron Browne © 2007. Last modified 18/7/2007.