Rules
Board game where two (or more) players place atoms on hexagons until these explode and distribute atoms around, causing chain reactions.
The board consists of hexagons arranged in a honeycomb pattern. Players take turns. During each turn, a player places a new atom they own on a hexagon that is either empty or occupied by the player's own atoms.
As soon as a hexagon acquires at least as many atoms as it has nearest neighbours, it explodes and one atom is distributed to each neighbour while turning any atoms already on these neighbours into atoms of the player who triggered the explosion.
An explosion can cause neighours to immediately explode, too, and trigger a chain reaction.
The goal is to turn all other players' atoms into your own.
History
This game has been modeled after two games I encountered years ago, both being played on a checkerboard.
The first was called Sprengmeister (German for "demolition master") running on an Atari ST. In Sprengmeister, explosions happened one at a time, so a symmetric distribution of atoms may become unsymmetric during explosions.
The second was called Atomic, and I don't remember whether it was on Atari ST or Intel x86. I also don't remember whether it handeled explosions consecutively or concurrently, but I do remember that it had some bugs and crashed on occasion.
Oliver Ruebenacker, June 5, Cambridge, MA, USA