If you want to, you can invent a completely new sport for your game, but this approach is not always a commercial success. Sports games also include two features not usually found in other games: weather and instant replay (the ability to watch an action again in slow motion). This section addresses these issues, which don't generally apply to other genres.
From time to time, someone tries to create a sports video game of a completely invented sport as opposed to a simulation of an existing one. Experience shows that this is a risky enterprise. Hardcore sports gamers seldom take an interest in completely new sports; they'd rather play a game that simulates a sport they're already familiar with. Other types of gamers aren't particularly interested in sports games anyway, so they aren't very likely to want to play a one-off sports game unless it appeals to them for some other reason. If you're thinking of inventing a new sport, you should design it primarily as a video game rather than designing it as an athletic sport for humans to play and then converting it to a video game.
This is how Empire Interactive designed Speedball; although theoretically a sport, Speedball includes powerups and other arcade-game elements to make it more interesting to people who don't normally like sports games.
One of the trickiest aspects of sports game design is mapping real-world activities to a limited input device. Players are willing to tolerate some awkwardness in the user interface when it's a real sport because they understand the problems, but with an invented sport, they're unlikely to be so generous. When designing a completely new sport, you might consider working backward from the controller to the sport itself, designing around the limitations of your hardware.
Many sports have special rules regarding weather conditions: Rain stops play in baseball but not in football, and so on. The weather can definitely affect the play. Rain and snow make traction difficult, reducing the athletes' ability to accelerate and lowering the top speed that they can reach. Equipment becomes slippery and more difficult to control when it's wet. Hot, humid days cause athletes to tire out
more easily. Think about how the weather affects the athletes, playing field, and equipment, and adjust your core mechanics appropriately.
Instant replay is now an essential part of watching sports on television, so naturally video game players want it as well. To implement instant replay, your game will need to keep track of the exact position and animation step of every athlete and all the equipment on the field or be able to reliably recreate them. The amount of data storage available will limit how much information you can keep around in case the player wants to see it again. When possible, select natural boundaries in the game - play as the point to begin recording: in baseball, when the ball is pitched; in American football, when the ball is snapped. In continuously flowing games such as basketball, you might need to establish an artificial time limit.
A good many games now show an instant replay automatically after important events, to better re-create the experience of watching the sport on television. Some players find this annoying, however, because it breaks up the flow of the game. All sports games should include instant replay, but players should be able to interrupt the instant replay and to switch the automatic replay off if they want to. Wii Sports provides an automatic instant replay that the player can interrupt by pressing the A button.
The best instant-replay mechanisms allow all the following features for maximum flexibility:
■ Play, stop, fast-forward, rewind, and single-frame advance and reverse operations to allow the player to see exactly what happened at every instant.
■ The ability to move the camera in all three dimensions to a different position above the field or court, and to pitch the camera up and down and pan left and right. (This assumes you are using a 3D graphics engine. With a 2D engine you should at least allow the player to move the camera around unless the field or court fills the screen.)
■ The ability to lock the camera to a given athlete or to the ball in order to follow that athlete or ball wherever it goes. This is usually done by showing a symbol on the ground that represents the camera's focus of attention. If the symbol is directly under an athlete's feet when the player stops moving the camera, the camera locks onto that athlete.
Instant replay lets the players see the action from perspectives that they can't use when actually playing the game. For the game's publisher and developer, this kind of instant replay is an invaluable tool for grabbing dramatic screen shots or game - play footage for sales and demonstrations. You should consider it an essential feature of any sports game that you design.