Rules

Back to the game.

Overview

Boop is a game for two players, played on a 6×6 square grid with 8 small pieces (“kittens”) and 8 big pieces (“cats”) per side. Players alternate placing a piece of their color on the board. A player wins the game when, at the end of their turn, they have an alignment of three big pieces of their color (in any direction including diagonals), or they have all 8 of their big pieces on the board.

Initially, each player has 8 kitten pieces in their reserve and the cat pieces are not in play.

The yellow player starts.

Turn Resolution

On their turn, the active player must:

1. Pick a piece from their reserve and place it on an empty cell on the board.
2. Displace neighboring pieces (see “booping”)
3. Resolve potential win conditions or graduating conditions.

Booping

When a piece is placed on the board, it will displaces (“boop”) its 8 potential neighbors according to the following rules:

1. A kitten will displace another kitten, but not a cat.
2. A cat will displace a kitten or a cat.
3. A piece will displace neighbors of either color.
4. Displaced pieces move one cell away from the piece that was just placed if the destination cell is empty or off board. If the destination cell is occupied, they don’t move.

If a piece is displaced off board, it goes back to the reserve of the player whose piece was displaced.

Winning Condition

If a player ends their turn after booping with either of:

1. An alignment (in either of the four directions including diagonals) of three cats on the board.
2. All of their pieces on the board, if they are all big pieces.

A player can only win on their turn.

Graduating Condition

If a player has three of their pieces (of any size) aligned in consecutive cells in any of the four directions (horizontal, vertical, diagonals), the triplet “graduates” as follows:

1. Graduating cats go back to the player’s reserve.
2. Graduating kittens become cat and go to the player’s reserve.

If all three pieces are big, the game is won and there is no graduation.

If the player manages to create multiple distinct triplets on their turn (for example with 4 aligned consecutive pieces), they decide which of the triplet graduates. They must chose exactly one.

If the player ends their turn with all of their pieces on the board, and at least one of them is a kitten, they have to choose one of their pieces and put it in the reserve. If they choose a kitten, it comes in the reserve as a cat instead.

If a player achieves both the “all pieces in” and a triplet during the same move, they must choose between graduating:

1. Exactly one of the triplet; or
2. Exactly one of the piece (by itself). It doesn’t matter if that piece is currently part of a triplet.

Clarification

What if I form a triplet for my opponent during my turn?

This triplet does not graduate on your turn. Assuming the game hasn’t ended, the opponent will have a chance to graduate this triplet on their next turn if that triplet is still on the board at the end of their turn.

If I create a big triplet for myself and my opponent in the same move, is this a draw?

Winning conditions and graduating conditions are evaluated for the current player only. This situation would not be a draw, the first player to create a big triplet on their turn wins even if they also create a big triplet for their opponent at the same time.