You play as Red against Blue.
Click anywhere on the board to create a random wall maze. The creation of the maze might take a few seconds.

Then the players alternate dropping balls into the maze at any position except at an intersection.

The system will add balls of your colour at 'maze-adjacent' positions up to the next intersection. Once an intersection has only 2 open paths left, it does not count as an intersection anymore for the next move.

To compensate for the first player's advantage, the first player's first drop will not be expanded by the system, but result in only one ball to be dropped! (However, the first player can use this one ball to cut the longest path in two pieces, for example.)

The game is finished when all positions are filled.
The player with the most balls (i.e., covering the most area) wins.
To give the players some information who is ahead during the game, counters for the red and blue balls are displayed the right border.

The Zillions AI plays this game very strongly on the 15x15 board. (Give it at least 5 seconds per move).
On the 25x25 board, it is clearly overwhelmed and needs at least 1 minute per move.

Variant 2: uses 25x25 board.

 
The name 'Maffy' is derived from 'Maze-Fill'.

Related Zillions game: Walls (which is a version of the popular game 'Boxes').
In contrast to 'Walls' (or 'Boxes'), in Maffy you have a nice maze given as a playing board, which improves the board design and speeds the game up, since the players do not have to construct the walls in a lenghty and (on a large board) quite boring setup phase.
A further difference is that in Walls (Boxes) the players can claim an area at any time, before a maze is built.
Finally, the special first-drop rule in Maffy balances the power between the players.

Other Zillions maze games: Bigmazes, Bigmazes II, Bigmazes III, 3D-Mazes, Maze Haven, Maze Maven, Lost In The City.

A discussion of maze algorithms can be found at http://www.astrolog.org/labyrnth/algrithm.htm.
This script uses the Hunt and Kill method.