Every business sits in a network of four player types: customers and suppliers on the vertical axis, competitors and complementors on the horizontal axis. Mapping all four forces you to see cooperative relationships you would miss if you only looked at rivals.
A complementor is any player whose product makes your product more valuable to customers (hardware and software, cars and loans). Competitors shrink your pie by making customers value your product less when they also have the rival's; complementors expand it, so the same player can be both at once.
Strategy has two distinct activities: creating value (growing the pie, which is cooperative) and capturing value (splitting the pie, which is competitive). Treating business as pure war misses that you must first cooperate to create a market before you can compete to divide it.
Your added value is the size of the total pie with you in the game minus the size without you; this caps what you can claim in any bargain. To capture more, either raise your own added value or lower that of others, for example by limiting supply so each unit becomes more essential.
Players treat the game as fixed, but its elements (Players, Added values, Rules, Tactics, Scope, summarized as PARTS) are all changeable levers. The higher-leverage move is often to alter who plays, the rules, or perceptions rather than to out-execute rivals within the existing structure.
The authors describe a dominant firm that can be better off paying a competitor to stay in or enter a market, because a credible second source raises customers' willingness to commit and sign larger contracts. The counterintuitive move shows that a monopolist's added value to a buyer can be low precisely because the buyer has no alternative.