Shooting Java Cowboys

Four Java Cowboys are in the room. Each has money and can shoot and kill others to try and get more. Survivors with enough money will reproduce passing on their personality. The personalities are the interesting thing; some are more aggressive, some more selfish, some more cooperative. The question is what personalities or blend of personalities lead to stable populations. Initially, I expected results to show that a population is most stable when the majority keep the peace, work, and don't start trouble with just a few others to take advantage of them - to keep things stable.

Development is at SourceForge

Code is all Java and runs as an Applet. An RMI back end tracks the population as it changes. The backend server is currently down as I just have moved to Oregon and don't have DSL. Real time statistics are therefore not available; some cached stats are here Current generation, Archived generations

The basics

On his turn a cowboys can pass or shoot at one of his brothers injuring or possibly killing him. Each shot detracts a certain amount of D&D style health.
When a cowboy does kill another, he gains his money minus tax.
The round ends when all surviving cowboys pass.

The Strategies:

Each cowboy has a strategy. This strategy determines how the cowboy will play. The name of the strategy is visible in the central control applet.

Beavis - Shoot a random player.
Vegetarian - Never shoot.
Moral - Shoot the last living player that shot you or pass if none exists.
Greedy - Shoot the richest player.
Sneaky - Shoot the player with the highest expected payoff that is over $500 (depends on your accuracy, tax, their health, and how much money they have.)

Each Round

Theme: modified prisoner's dilema - you gain by killing the other guy, but not as much as he loses.

At the start of each round, 4 cowboys are picked from the population (randomly and uniformly.)
Surviving cowboys get a survival bonus.
At the end of the round:
- Dead cowboys are removed from the population.
- Surviving cowboys heal to 100% health.
- Surviving cowboys also get a survival bonus on top any money that they've accumulated during the round.

Each Generation

Theme: natural selection - successful cowboys breed. The most successfull behavior depends on the rest of the population..

The population is randomly generated at the start (not uniformly).
Any cowboy with more than twice the starting amount of money, will breed - give life to a new cowboy with the same strategy and the starting amount of money.
As rounds take place, some cowboys gain money and breed and others die off.
The generation ends when the population drops below 4 or has trippled.

The basics

The Strategies:

Each Round

Each Generation

Questions? Comments?