*Star is a complex abstract strategy game by Ea Ea, a designer of Y. It is a redevelopment of his earlier game Star.

Notation

thumb|right|upright=1.2|Representation of the *Star game board, partially labeled.

Each cell on the game board is labeled with a three-character value Nxy according to a polar coordinate system:

  • N refers to the primary radial arm. There are five arms, labeled as *, S, T, A, or R, proceeding clockwise from the point of the lower right arm of the five-pointed star in the middle of the board
  • x refers to the ring number of the cell. The concentric rings are labeled from 1 to 10, using the rightmost digit only, with Ring 1 (x=1) in the center of the board and Ring 10 (x=0) on the perimeter of the board.
  • y refers to the tangential position of the cell, counted clockwise from the radial arm. For example, in Ring 3, the cells would be labeled *30 (for the cell on the "*" primary radial arm), *31 (for the cell immediately clockwise within the same ring), *32, S30, S31, S32, T30, ... R31, R32.

This board illustrated here has sectors colored corresponding to the primary radial arms to distinguish the tangential positions (in this example, the "A" sector is colored green). In the game, the board is a single, uniform color.

The perimeter cells (in the ten-ring example illustrated, N0y) are called the pericells and each contain one peri. The five corner pericells (N00 for the ten-ring example) each have one quark associated with them.

thumb|right|upright=1.2|*Star game board as a mesh of nodes instead of cells.

The *Star board can also be represented as an equivalent mesh of nodes instead of cells. The same Nxy nomenclature may be used to refer to each node instead.

Rules

*Star can be played on graphs of different sizes. The small, medium, and full boards shown below have 105, 180, and 275 nodes, respectively, of which 30, 40, and 50 are on the perimeter, respectively. Note the five-pointed star in the center acts as a bridge which links the five centermost nodes to each other.

<gallery mode=packed heights=200px>

Image:star6.png|A small *Star board (6 rings, 105 nodes: 30 perimeter and 5 corner nodes)

Image:star8.png|A medium *Star board (8 rings, 180 nodes: 40 perimeter and 5 corner nodes)

Image:star10.png|The full *Star board (10 rings, 275 nodes: 50 perimeter and 5 corner nodes)

</gallery>

Two players alternately place stones of their colour on empty nodes. The game ends when the board is filled up (or when both players agree that the score is decided).

Each node on the perimeter of the board contains one peri. Each corner node contains one quark in addition to the peri for being a perimeter node. A star exists when a connected group of a single color owns at least two peries. A peri is owned if it is either directly occupied by that star, or if the peri is enclosed by the territory occupied by the star.

The game is scored by the sum total of:

  • 1 point for each peri owned (occupied or surrounded)
  • 1 point to the player with three (or more) quarks (the quark peri)
  • An adjustment reward based on the relative number of stars per player

For clarification when computing the score, groups owning fewer than two peries may be removed, making it clear those peries are owned by the surrounding star.

The reward adjustment is computed as the difference between the number of stars the other player has and the number of stars owned by the player, doubled. Effectively, it penalizes the player with more stars and rewards the player who has more effectively grouped their stars. The player with the higher adjusted score wins. In the event of a tie, the player with the most quarks (corners) wins.

Comparison to other games

*Star is closely related to the games Hex and Y where the goal is to connect certain sides of the board to each other. On the other hand, *Star also is closely related to Go in which the goal is to gather more territory than the opponent. Often survival of a group in Go is achieved by connecting it to another one. In Go, all the surrounded area is counted as territory although in practice most of the territory is gathered near the perimeter. Because UCT search was used previously to provide a play-out method for Go, researchers in Finland successfully used a similar algorithm to create a strong computer-based player for *Star in 2008.

John McCallion reviewed the game for Games in March 2005, calling it "intriguing" due to "the continuing dilemma that players face" of having to balance scoring by occupying perimeter cells with the need to connect as many scoring groups as possible.

References

  • *Star homepage