Evening is created as a family game of Alexander Brady's Interleave.
Like Interleave, it is a turn-less game, and instead of the sightline placement restrictions of the original game, it uses placement restrictions based on group size superiority.
Setup
Use a regular hexagonal board of any size (size 5 is preferred) and a sufficient number of black and white stones. The white player begins the game by first placing one white stone in any empty cell.
Groups
A subset of stones of the same color that are adjacent to each other on the board is called a group. The size of a group is the number of stones it contains. A single stone is also considered a group of size 1.
Gameplay
You can only place your stone in an empty cell where the sum of the sizes of your group adjacent to it is smaller than that of your opponent's group. The number of cells available for placement is recalculated each time a piece is placed.
Game End
The owner of the largest group wins. If the largest group is tied, the next largest group continues to be compared until a difference occurs. If all groups are tied, the black player wins.
Variant: Odd-Even protocol
The white player is responsible for the "odd" pieces and the black player for the "even" pieces.
If all groups are tied in size, the number of pieces of one color (whichever is chosen is equal) is counted. If there are an odd number of pieces, the player responsible for the odd number wins; if there are an even number of pieces, the player responsible for the even number wins.