Match-three board rules

Represent a match-three board as cells with tile types. A valid swap should create a match or return both tiles to their starting positions, giving the player clear feedback.

Find matching runs before removing tiles, then apply gravity and refill. Repeat resolution until the board is stable, and decide how to handle a board with no valid moves.

This page is a readable game-design exercise. It provides study notes and related tutorials; an interactive game is not embedded.