Explocus was invented by dutch game designer Martin Medema. Ed van Zon translated the game to the hex grid.

explocusHybrids usually make bad games, like Lasca mixing checkers with the 'column capture' mechanism. Occasionally though something new and original emerges, like João Pedro Neto's Gonnect, using the rules of Go for a different objective, or indeed Martin Medema's 'Explocus'.

As it happens, I was present at its first presentation at the games club Fanatic at the University of Twente, and I'd never seen a game with such capricious tactics and such dramatic turns of the proverbial tables.
As it turned out, I'd even played a minor role in it. At the time I had a subscription to an english magazine called Games & Puzzles and I had even ordered all back issues. In one of them a game called 'explosion' was described (see list).

Martin had put the mechanism it was based on - towers of men 'exploding' the moment their height reached or surpassed the number of neighboring squares - to a far better use by employing the 'Focus' rules of movement. A very lucky merger resulting in a most unusual game. If anything could be said against it, it might be that the game has no mechanism to terminate it.

  • The diagram shows the board with the pieces in the initial position. Players move, and must move, in turn. White begins.
  • A piece may be a single man or a column of like color of two or three men high. 'Mixed' columns are not possible in Explocus.
  • On his turn a player must move one of his pieces, which may be a single man, or a whole column, or part of a column, that is the top man or the top two men.
    The move must be in a straight (i.e. orthogonal) direction, and exactly as far as the moving piece is high, that is: 1 square if a single man moves, 2 squares for a column of two and 3 squares for a column of three.
    The target square may be vacant or occupied by either player. If occupied by an opponent, the man or column present there will immediately change color.
    Note: In actual over-the-board play this was rather cumbersome. Here the applet comes to the rescue.
  • Definition:
    The 'capacity' of a square equals the number of (orthogonally) adjacent squares it has, that is: 4 in the center, 3 on the sides and 2 in the corners.
  • If a piece landing on its target square causes this square to reach or surpass its capacity, the column concerned 'explodes', that is: its men are distributed, one on every adjacent square, while any remaining men stay on the target square. Any opponent's pieces thus covered, again immediately change color.
  • Chain reactions:
    If men exploding onto adjacent squares in turn cause these squares to reach or surpass their capacity, the columns concerned explode likewise, which may lead to an extended chain reaction that eventually comes to an end. If a player is faced with more than one exploding square, he is free to choose the order in which to execute the explosions.

  • The object is, not surprisingly, to eliminate all the opponent's pieces.

An Explocus program only needs a simple evaluation function to outplay humans almost invariably. Ed has implemeted the game on the Zillions game machine, as well as its hexagonal version Zillions Hexplocus.

Explocus and its hexagonal twin are also implemented on the Axiom Game Engine and can be downloaded via our Axiom page.

Sorry, you need a Java enabled browser to view the Focus Player!

Using the Explocus applet

Explocus © Martin Medema
Java applet © Ed van Zon