Chess on a Mass Transit System

You and your opponent are struggling for control of your favorite city's mass transit system, but you're both stuck with fickle, easily-converted troops. Whenever the other side lands an agent on a spot covered by your forces, your forces switch sides. So to win the control you seek, you need to convert all the forces to your own side.

Setup

First the players need to agree on a transit system. You and your opponent can choose an already exisitng system or you can develop a fantasy system in the following manner:

1. Pick the number N of "stops" you are going to have.
2. Place and label N dots (or chips, or thumbtacks, or widgets) on your playing surface
3. Determine the number of routes that will be created.
4. Take turns creating routes. A "route" is a sequence of stops and should be indicated on the playing surface by drawing line segments between the successive stops on that route. Each route should be distinguishable from all the others. Each player can specify one complete route during each of his or her turns.

Next the players need to decide on the number of pieces of each type. I suggest 1 Pedestrian per 8 stops, 1 Rider per 16 stops, 1 Transfer Rider per 32 stops, and 1 Chief.

Next the players take turns placing their pieces one at a time on the board. Each piece must be placed on a stop, and no piece may be placed on a stop that already has an opponent's piece.

Pieces

There are four piece types:

• Pedestrian: Can move to the next stop on any route that goes through the stop it currently occupies.
• Rider: Can move to any stop on any route that goes through the stop it currently occupies.
• Transfer Rider: Can move to a stop if there is a path to it from its current stop that uses exactly two routes (i.e., the transfer rider always makes exactly one "transfer" in going from its start to its destination.)
• Chief: Can move like a Rider or a Transfer Rider.

No piece may pass through a stop occupied by an opponent's piece. A piece may either land on or pass through a stop occupied by friendly pieces. There is no limit to how many friendly pieces may be at the same stop.

Rules

1. The first player is chosen randomly.
2. A player moves exactly one of his or her pieces per turn.
3. If a player lands a piece at a stop occupied by the opponent, all the opponent's pieces become the player's pieces.
4. A player wins when he or she has converted the last of the opponent's pieces.

Notes

This variant is inspired by the N-squares Variant Contests sponsored by the Chess Variant Pages. If the N-Squares contests ever resume, I want to be ready :-). This variant is also inspired by other "big idea" chess variants, such as Ralph Betza's Chess for Any Number of Players. The conversion idea comes from Dan Troyka's Benedict Chess. Allowing friendly pieces to pass through other pieces is an idea that was proposed for the committee-designed chess variant Lùotuoqí.

Any suggestions or comments are welcome.