Fun Match 3 game. Click to remove a tile. Press "R" to reload the game.

The game mechanics are as follows:

The game consists of m x n tiles (configurable in editor or code).
If three or more of the same tile type are in a horizontal row, the game removes them.
A tile falls down if there is no tile below it (unless it's on the bottom row).
The user can click on a tile. The game then removes the tile.
When the game starts, all the positions should be filled with tiles and nothing should fall down.

Limitations:

Do not use the physics engine to move the tiles.
Do not use raycasting for anything except if required to detect what tile the player clicked on.
Apart from Unity's built-in functionality, do not use any plugin, external library, or code you didn't write yourself.