Momentum

Momentum is a tactical abstract board game for two players in which the lead swings back and forth like the spheres of Newton’s cradle.

Components

Momentum is normally played on a 7 x 7 game board but can be played on game boards of various sizes and shapes. Players will need an adequate number of stones which represent marbles. See the chart below and the Variants section.

Figure 1. Green to drop a marble in the cell marked with an 'x'.

Figure 2. After the drop. The arrows indicate the effects of momentum. Two red marbles and one green marble are returned to their owner.

Setup

The board is empty at the start of play. Players select a game board size and both players start with their own set of marbles in reserve. Players decide who will go first.

Game Play

Players alternate dropping marbles on empty cells.

The last marble of each line of one or more marbles radiating outward from the dropped marble is pushed one cell directly away from the dropped marble. The momentum of the dropped marble radiates in all eight directions (orthogonal and diagonal). However, if there is no marble adjacent to the dropped marble in a given direction, no marbles will be push away in that direction. The momentum pushes any last marble, regardless of color, away from the dropped marble. See Figures 1 and 2.

Marbles that are pushed off the board are returned to their owner’s reserve to be dropped again later.

Pie Rule: On the second player’s first turn only, the second player may either drop a marble or replace the first player’s dropped marble with one of his or her own. In either case, play continues with players alternating turns dropping one of their marbles onto any empty cell.

Winning the Game

The first player to have all his or her marbles on the board at the end of his or her turn, after all momentum is resolved, wins the game. As a courtesy, a player should announce last marble if he or she has only one marble left in reserve. By far, most Momentum games will end this way but there are exceptions.

There are two occasions when a game can go on and on like a perpetual motion machine.

The first is when both players decide it is in their best interest to make the same moves over and over again.

The second occasion is when players are evenly matched and neither player is able to force a win. An average game of Momentum on a 7 x 7 board should last between 15 and 20 rounds or 30 to 40 player turns. Games that last 30 rounds should be considered perpetual and concluded using the following rule.

30-Rounds Rule: (Optional, but recommended for beginners): If a game lasts for 30 rounds, play stops and the outcome is determined. If either player has a majority of marbles on the board that player wins, if not, the game ends in a draw.

Tip: Players can use a spare token to keep track of rounds by using the edge of the board. Once around a 7 x 7 board is 28 steps (not counting the corners). Two more rounds and the game ends.

Download and Play

Click here to download the Flash version of the Momentum. The game is not a "finished" product. It was created to play test Momentum. It does move marbles for you and you can even play through a game in progress and revert back to a move to study different threads. There is no AI due to Flash limitations.

Variants

Board Shape: Rectangular, hexagonal and irregular boards can be used.

Multiple players: Momentum can be played as a three- or four-player game. Player turns pass to the left. In the three player game, a player must prevent an immediate win by his opponent to his or her left and is not obligated to block the player to his or her right. Four player games should be played in teams of two.

Obstacles: The board can be made more challenging by adding cushions or holes to symmetric or randomly selected cells. Marbles can not be dropped on these special cells.

Cushions adjacent to the last marble of a connected line of marbles absorb the momentum so that the last marble does not move.
Holes add internal edges to the game board and are a way of creating an irregular game board. Marbles moving into a hole are returned to their owner as if they fell off the edge of the board.

Designer Comments

Momentum, at first, is a perplexing puzzle - it seems like it could go on forever. This, in my opinion, is what makes Momentum fascinating and a worthy challenge. After over 3000 plays at igGameCenter, the average game of Momentum lasts under 11 minutes and between 15 to 20 rounds. It is fast and, with marbles flying all over the place, a whole lot of fun.

Acknowledgement

I want to thank Arty Sandler for adding Momentum to his impressive collection of online games at his site IGGAMECENTER. I also want to thank all the game center players who played Momentum and put it at the top of the charts for many weeks. Of special note are the players vit555, bajvik, and dave doma who have played 650+, 280+ and 230+ games respectively. Awesome! Thanks to all the iggc players, Arty Sandler, and Sylvain Rochon of Sylien Games, Momentum was given an AI bot and later became an app for the iPhone! Finally, I would also like to thank Néstor Romeral Andrés for publishing Momentum. Please visit his outstanding "fun to take away" games site, NestorGames.

Please note that these game rules may be duplicated and distributed via the web but the rules may not be altered and full credit must be given to the designer, Phil Leduc. Otherwise, all rights are reserved. Those that wish to program or sell this game in any form should contact the author at philleduc.pled@gmail.com for permission or a license to do so.