How do I add special gems into this match-3 game?
For example:
4 gems in a row: A fire gem that, if matched, explodes in a 3x3 radius;
5 gems in a row: A "hyper-cube" or "colour bomb" that, if swapped with any gem, will destroy all gems of that colour;
5 gems in "L" or "T" shape: A lightning gem that, if matched, will destroy every gem along its X and Y axes;
Randomly spawns in when new gems fall onto the board: A bomb gem that counts down every move, and, if the counter reaches 0, ends the game.
Another random thing: Levelling up when the player reaches a certain amount of points.
