Copyright (c) 1984 Christian Freeling

This game is played on a 9x5 square board with the following setup:

WALL - The dotted cells of the diagram.
STACKS - One or more stones stacked together.
Stacks have a maximum capacity. Two stones at the three central columns, and just one at the side columns.
Explosions - If a stack exceeds its capacity, it explodes. Then, it shoots its stones to the adjacent forward and sideways cells.
For the central columns: one man forward, one to the left and one to the right
For the side columns one man forward and one sideways
The remainder, if any, stays on the original cell
If one of those cells are occupied by an enemy piece, that piece is captured. There's an exception: if the enemy piece is at the last row, it is the stone from the exploding stack that's captured.
An explosion may produce a chain reaction. If more than one stack must explode, it is the player that defines the order of those explosions. 
MOVE - A piece moves diagonally forward or backward any number of empty cells.
When moving forwards (not backwards) the piece stop if it reaches a wall.
On top of a wall, the piece cannot move forward, except by explosion.
A piece may stop on top of a friendly piece (and both are stacked together). The new stacked piece has the same moving capabilities.
TURN - On each turn, each player moves a piece or pass his turn.
GOAL - Wins the player that moves one of his pieces into the last row.
An example

White may open by moving b2-a1 producing an explosion and a chain reaction. The a1 stack explodes sending one stone to b1 and another to a2. Then the b1 stack also explodes, moving a stone to c1 and another to b1. The left diagram shows the final position.

Some words from the author: Strategy is obvious: you need an explosion from the far wall to get beyond. Side columns explode fastest, so A7 and E7 appear obvious targets for white to get two men on. The drawback of this strategy is that, if successful, it gets a man across on the sidecolumn on A8 or E8, where a defender can block it with a single man on B9 or D9. If however the attacker next successfully targets the same square again by a second explosion from the same square on the wall he wins because this would cause the square on the eighth row to explode. Breakthrough was featured in Games Magazine (january 1984), but has since then undergone a minor change in the rules.