Creating Your Own Game - C# Game Programming: For Serious Game Creation - page 406

traditional tile-based approach by using an overhead camera that looks down on
the players and game world. Diablo 3 and Twilight are two good examples of this
style. The third option is the third-person camera that one might see in Zelda
since the N64 era, or the Mass Effect games.
The FPS-based approach puts you inside the eyes of the character, encouraging
immersion in the game world. To start this kind of game, you would first need to
be able to make a simple FPS game. FPS games tend to take place in tight
buildings separated into missions or levels; RPGs tend to have big open areas and
a large game world. Open worlds that allow a character to seamlessly walk from
one city to another are very hard to program; data must be loaded and unloaded
dynamically as the character walks around the world. This is very hard in an FPS
game because if the player manages to climb somewhere quite high, then he
expects to be able to look out onto the world and see where he has come from.
This means a low-detail version of the world needs to be present in memory
most of the time, and areas need to become more detailed as the player ap-
proaches. If this kind of algorithm interests you, then I suggest searching for
papers on ROAM (Real-time Optimally Adapting Meshes). As with other games,
it's a good idea to start small and simple and take small steps to something more
complicated.
An easier approach to the open-world problem is to confine the player to small
areas that can be loaded in memory all at once. Games such as System Shock and
Bioshock use this limitation to drive the story. In System Shock, you are confined
to a space station, and you can only move to different levels using a central ele-
vator. While the elevator is moving, the old level is unloaded and the new level is
loaded in. Bioshock works in a very similar way, but it's an underwater base.
Third-person games are very similar to FPS games, but the camera is pulled back
allowing the player character to be seen on screen at all times. There are still the
same problems with representing a vast dynamic world on only a limited
amount of memory and computer resources. The Mass Effect games split up the
world by scattering the levels over different planets. While the player is dis-
embarking from his ship to the planet surface, the level is loaded. Zelda games
have either an explicit loading screen as one area is loaded and another unloaded,
or sometimes a dog leg is used. A dog leg is a stretch of level where nothing can be
seen apart from the narrow corridor the player is walking down. The shape of
the corridor is roughly like a dog's leg, or a very relaxed L shape. The corridor is