have thousands or even millions of players, professional wargames tend to have small player bases, which makes it harder for the designers to acquire feedback. Consequently, errors in professional wargame models tend to persist. Although commercial wargame designers study consumer trends and listen to player feedback, their products are usually designed and sold with a take-it-or-leave-it approach. Professional wargames, by contrast, are typically commissioned by the military that plans to use them. If a wargame is commissioned by several clients, then the designer will have to juggle their competing demands. This can lead to great complexity, high development costs, and a compromised product that satisfies nobody. Commercial wargames are under more pressure to deliver an enjoyable experience for the players, who expect a user-friendly interface, a reasonable learning curve, exciting gameplay, and so forth. By contrast, military organizations tend to see wargaming as a tool and a chore, and players are often bluntly obliged to use whatever is provided to them. Professional wargames that are arbitrated by an umpire or the players themselves (manual wargames) tend to have simple models and computations compared to recreational wargames. Umpires may even be allowed to make arbitrary decisions using their own expertise. One reason for this is to keep the learning curve small. Recreational wargamers tend to have a lot of wargaming experience (it is usually considered a hardcore hobby), so learning a complicated new wargame is easy if it is similar enough to ones they've already played. By contrast, military officers typically have little or no wargaming experience. A second reason is that the technical data required to design an accurate and precise model, such as the performance characteristics of a fighter jet, is often classified. Overview The exact definition of "wargame" varies from one writer to the next and one organization to the next. To prevent confusion, this section will establish the general definition employed by this article. A wargame simulates an armed conflict, be it a battle, a campaign, or an entire war. Business wargames do not simulate armed conflict and thus fall outside the scope of this article. A wargame is adversarial. There must be two opposing sides whose players react intelligently to each other's decisions. A wargame does not involve the use of actual troops and armaments. This definition is used by the US Naval War College. Some writers use the term "live wargames" to refer to games