ATOMS

Copyright (c) 1981, 2000 Robert A. Kraus

The game is played on a 8x8 square board. Each player begins with 11 stones off-board. 

PLACING - On the first turn White drops an atom on any cell; then players alternate placing atoms on any empty cell which is adjacent to exactly one other atom (of either color). After all atoms are placed they form one large molecule, which may split into several smaller molecules during the game. VALENCE - Each atom has a valence, which is the number of atoms (of either color) adjacent to it (include diagonal). MOVING - Players must now move one of their atoms to any adjacent empty cell provided that its valence in the new position is exactly the same as its valence in the old position. CAPTURING - Any atom which is not adjacent to an enemy atom is unstable. Immediately after each move, the players remove all unstable atoms from the board. This also occurs after Black makes his last drop. GOAL A player wins by stalemating his opponent, (leaving him with no legal moves).  A player also wins by leaving an empty board (after the removal operation); in fact this is a special case of stalemate since his opponent would have no moves at all.

Some examples This is a possible position after the dropping phase.  Black atom at b7 has valence 2, so it can be moved to cell [1].

White has a winning position. If White moves atom at e4 to cell [1], the two Black atoms at e3 and d5 are captured, and then Black cannot move his last atom (it has valence 3, and there is no other adjacent cell with that valence).

R. Kraus defined two variants: Isotopes, where each atom can move any number of cells (instead of just being able to move to the adjacent cell); and Radioactive Atoms, where a stone may also commit suicide (if able to move to an isolated cell). There is a file to play Atoms with Zillions.