• Board and Pieces
• Objective
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Isaac is played on a 10x10 board.  There are two players: Dark and Light. Each player has 15 rectangular tiles of 5 different sizes. Each tile has a score written on it. Each player also has 1 score counter used in the second phase of the game (see below). Note that the board has two opposite grids of coordinates: one for the Dark player and the opposite one for the Light player. On the following illustration the bottom left corner of the board is 00 and the top right corner is 99 according to the Dark coordinates. The same corners have the opposite coordinates (00 for the top right corner, 99 for the bottom left corner) for the Light player.

Dark pieces			Light pieces
5 x			5 x
4 x			4 x
3 x			3 x
2 x			2 x
1 x			1 x
	- score counter			- score counter

The game consists of two phases: the placement phase and the scoring phase.

The placement phase begins with an empty board.

Starting with the Dark, players take turns placing one of their tiles per turn onto unoccupied cells of the board.

If a player cannot put any of his remaining tiles on his turn then he passes and the other player puts any tiles he can.

The placement phase ends when both players don't have space to put any of their tiles on the board. All the remaining tiles are set apart and serve the role of  the tiebreaker. If both players get the same score by the end of the scoring phase,  each player forms a line with all his unplayed tiles and the player with the longest line of the unplayed tiles wins the game. If the lines are of equal length, the player who started the game wins. Note that the length of each tile is not a round number of board squares but a little bit shorter.

At the beginning of the scoring phase both players have 0 points. To indicate this both players put their score counter on the 00 square according to their own coordinates (i.e. on the leftmost square of the line in front of them). If the mentioned square is under some tile, the score counter goes on top of this tile.

The first player that passed in the Placement phase begins the Scoring phase. The players take turns removing one of their tiles from the board. The removed tile must be at least as long as any tile previosly removed by the same player (e.g. if a player has previously removed a 4-cells tile then he can't remove his 3-cells tiles anymore). A player may not remove a tile lying under a score counter (of any color).

For each removed tile a player scores points in the following way:

• count the total number of tiles left lying on or crossing the line from which the tile was removed;
• multiply this number by the number written on the removed tile.
• If there is a single score counter (of either color) lying on this line then multiply the result by 2. If both score counters are lying on this line then multiply the result by 4.

The final result is the score earned by the removal of the tile. It indicates the maximum number of squares that the player's score counter may be moved. E.g. if the player's score counter is located on 45 and the player earned 24 points then he may move his score counter to any square from 45 (i.e. to leave it where it is) to 69 (45+24).

The counter may be placed over a tile (of any color) still on the board but not in the same cell as the opponent's counter.

The game ends when any player scores at least 100 points. If a player cannot remove any of his tiles on his turn, he passes and is out of the game. The game ends when both players have passed.

Below are several examples of scoring moves:

It is the turn of the Light player and the player decides to remove his highlighted tile, which is placed between the squares 04 and 44. Note that there are opposite coordinates for both players so the coordinates 04-44 should be checked on the Light edge of the board (top & right).		There are 5 tiles (4 light and 1 dark) lying or crossing the line from which the highlighted tile was removed. The number written on the removed tile is 3. In addition the dark score counter is located on the same line (05 using the Dark coordinates). So the final result achieved by the removal is 5 x 3 x 2 = 30. The Light player decides to use all the earned score and moves his score counter from the 00 to 30 (see the Light coordinates).
It is the turn of the Dark player and the player decides to remove his highlighted tile, which is placed between the squares 43 and 93 (Dark coordinates).		There is 1 tile crossing the line from which the highlighted tile was removed. The number written on the removed tile is 4. So the final result achieved by the removal is 1 x 4 = 4. The Dark player have several options to move his score counter: He can move his score counter to 38 and let the Light player make his last move. In this case the Light player would remove his last tile and score 12 points (6 x 1 piece on the line x 2 for the dark score counter on the line). The final score of the Light player would be 47 vs the Dark's 38. So the Light player would win. The Dark player can "sacrifice" the earned points and move his counter to 36 as shown on the above illustration. In this case the last Light tile is blocked and the Light player is out of the game. The Dark player (whose score is 36 vs Light's 35)  wins in this case without any use of the tiebreaker.
It is the turn of the Dark player and the player decides to remove his highlighted tile, which is placed between the squares 43 and 93 (Dark coordinates).		There is 1 tile crossing the line from which the highlighted tile was removed. The number written on the removed tile is 4. In addition the dark score counter is located on the same line (33 using the Dark coordinates). So the final result achieved by the removal is 1 x 4 x 2 = 8. The Dark player have several options to move his score counter: He can move his score counter to 41 and let the Light player make his last move. In this case the Light player would remove his last tile and score 6 points (6 x 1 piece on the line). The final score of the Light player would also be 41 so the Light and the Dark player would end up in the tiebreaker. The Dark player can "sacrifice" the earned points and move his counter to 36 as shown on the above illustration. In this case the last Light tile is blocked and the Light player is out of the game. The Dark player (whose score is 36 vs Light's 35)  wins in this case without any use of the tiebreaker.

• Rules of the game on BoardGameGeek.
• Youtube video explaining the rules.
• Buy this game on nestorgames.