Playing the game of business—and life—involves creating strategic alliances, and developing, managing, and ending those relationships as required. Skilled gamers quickly recognize both present and potential adversaries and allies, and they calculate tactics for converting useful opponents into partners—even, occasionally, to transform cronies into challengers. Why? Because, by definition, an enemy cannot betray you; only a friend can, so it’s important to choose them well. Whether in industry or on the world stage, good leaders know how to pinpoint the people who should be by their side; they’re also willing to make enemies who can be trusted to oppose them. Deciding who’s who is what matters, offering the potential of risk and reward. That’s how the game goes…and here’s how to win it.