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24 Networking and Online Games: Understanding and Engineering Multiplayer Internet Games

(c)

Figure 3.10 Screenshots of Warcraft. Warcraft I is shown in (a), Warcraft II is shown in (b) and Warcraft III is shown in (c). Reproduced by permission of Blizzard Entertainment, Inc.

developed a vigorous online community that even developed into several competitive leagues. Blizzard released Warcraft III in 2002, featuring new gameplay including Heroes and 3-D graphics (Figure 3.10).

The success of multiplayer gaming over the Internet was obvious, so Blizzard introduced Battle.net, an online gaming service. Like Kali, Battle.net was a virtual meeting place that permitted players to easily find opponents for Internet play. Use of Battle.net was (and is) free with the purchase of a Blizzard game. Battle.net essentially provided a meeting place for game players, complete with chat rooms and challenge ladders, but without Battle.net actually hosting the game in a client–server fashion (although games such as Diablo keep persistent characters and worlds on the Battle.net servers). This kept the bulk of the game traffic from passing through the Battle.net servers, saving on Blizzard’s hosting costs and increasing the scalability over a single, centralised client–server model.

3.2.4 Sports Games

Nearly as long as there have been computer games there have been computer games based on sports (see Atari Football in Chapter 2). Sports lend themselves to competition that naturally suggests multiplayer sports games. While the field of sports is nearly as varied as computer games themselves, two multiplayer online games that are popular and have been studied academically are American Football and Car Racing.

Figure 3.11 Screenshots of Madden NFL. The 1993 Sega Genesis version is shown on the left, the 2005 Microsoft Xbox version is shown on the right. Reproduced by permission of Electronic Arts.

Figure 3.12 Screenshot of pole position. Copyright Namco .

Establishing itself in the mid-1990s, Madden NFL Football (Figure 3.11), in its various versions, is the highest revenue-generating video game franchise in North America and in computer game history [MADDEN05]. Online play, however, was only introduced to the 2003 version and was only available for the Sony Playstation console or a Microsoft Windows PC. As of July 2004, Madden games are also enabled for online play on the Microsoft Xbox Live network. As of 2005, Madden only supports two-player games. Online services (such as for the Playstation or Xbox) via a centralised server enable opponents to locate each other, but players communicate in a peer-to-peer fashion directly with each other [NC04].

The first computer racing game that was released was Pole Position (Figure 3.12), popular in the early 1980s because of the quality of the graphics at the time [http:// en.wikipedia.org/wiki/Sim racing]. Although early versions of computer racing games

30 Networking and Online Games: Understanding and Engineering Multiplayer Internet Games

As of 2005, the hardware components of today’s consoles are as follows [Tys06]:

Sony PlayStation 2

• Processor: 128-bit “Emotion Engine”, 300 MHz

• Graphics: 150 MHz, 4 MB VRAM cache, 75 million polygons per second

•RAM: 32 MB RDRAM

•Other features:

◦Two memory card slots

◦Optical digital output

◦Two USB ports

◦FireWire port

◦Support for audio CDs and DVD-Video

Nintendo GameCube

• Processor: “Gekko” IBM Power PC microprocessor, 485 MHz

• Graphics: ATI 162 MHz, 4 MB RAM, 12 million polygons per second

•RAM: 40 MB (24 MB 1T-SRAM, 16 MB of 100-MHz DRAM)

•Other features:

◦Two flash memory slots

◦High-speed parallel port

◦Two high-speed serial ports

◦Analog and digital audio-video outputs

Microsoft Xbox

•Processor: Modified Intel Pentium III, 733 MHz

•Graphics: nVidia, 250 MHz, 125 million polygons per second

•RAM: 64 MB (unified for audio, video, graphics)

•Network 10/100-Mbps Ethernet, broadband enabled, 56K modem (optional)

•Other features:

◦8-GB built-in hard drive

◦5X DVD drive with movie playback

◦8-MB removable memory card

◦Expansion port

The next generation of consoles promises to be even more powerful [CNET05].

3.4.3 Handheld Game Consoles

Early handhelds were primarily single player. Multiplayer mode was generally enabled by players taking turns, as in Mattel’s Electronic Football, but some handhelds allowed two players to play simultaneously on the same device, sharing the display. Nintendo’s Game Boy, released in 1989 and the most popular handheld console ever, was the first handheld console to support networked multiplayer gaming. This was accomplished by

connecting a (short) wire between up to four Game Boys, and the game software could even be downloaded from one handheld to another.

The newest generation of handheld gaming systems are equipped with a wireless mode for multiplayer network gameplay. Sony’s Playstation Portable (PSP), and Nintendo’s Dual-Screen (DS) support the IEEE 802.11b wireless local area network (WLAN) standard. The Nintendo DS provides a specific subset of the features of 802.11b in order to save battery power for wireless network play. Notably, only a short preamble is used, and only the WLAN capacities of 1 Mbps and 2 Mbps are used, even though 802.11b supports capacities up to 11 Mbps, because these lower capacities consume less power. The Nintendo DS does not support any network layers above the 802.11 layer (in other words, no Internet packets), while the Sony PSP allows and supports Internet packets (IPv4) in the 802.11 infrastructure mode. This allows the PSP to connect to an Access Point (AP) and provide gameplay over the Internet.

The newest release of the PSP even includes a Web browser.

Nintendo DS

System

•Resolution 256 × 192, 260k colors

•Dual ARM processors

•ARM 9 at 67 MHz, ARM 7 at 33 MHz

•4 MB RAM

•Touch-pad

Network

•WLAN is IEEE 802.11b

•Short preamble

• Wireless capacities of 1 Mbps or 2 Mbps, only

•Ad hoc mode (peer-to-peer)

•No IP stack (UDP/TCP)

Sony PSP

System

•Resolution 480 × 272 pixels, 24-bit color

•Dual MIPS R4000 processors at 333 MHz

•32 MB RAM

•Analog joystick

Network

•WLAN is IEEE 802.11b

•1, 2, 5.5, 11 Mbps

•Ad hoc mode (peer-to-peer) and infrastructure mode (Internet)

•IP stack

Figure 3.20 Real people playing Rugby. Do not underestimate the immersiveness of Physical Reality!. Reproduced by permission of Tiffany Wolf.

with the game objects being tangible and concrete. The variety of such physical reality games range from sports, such as cricket and rugby (Figure 3.20), to board games such as chess and backgammon. While games in this cluster are generally not computer supported, there can be computers enhancing aspects of the game. For example, sensors and computer equipment allow accurate calling of the boundary lines in professional tennis. In addition, asynchronous communication by computers can allow games to be played without participants being in the same physical location. For example, chess can be played by two people who are geographically separated and use email or even VoIP to communicate their moves to their opponent.

3.5.2 Telepresence

Telepresence uses computers and networks to provide a feeling of immersiveness for a user that is physically separated from the environment. Sensors gathering information on the local environment transmit information to a physically separated user, providing feedback that allows some recreation of the local world from the remote location.

With telepresence, managing latency is critical for providing a feeling of immersiveness. In the local world, an action has an immediate consequence, whereas in telepresence, an action done remotely is delayed by the time it takes to travel from the remote user to the local environment, plus any additional processing time. Force feedback, where tension or pressure occurs from physically manipulating the local environment, is also often necessary to make the remote user immersed in the local world and can often help overcome deficiencies in the display from a low resolution or frame rate [MS94].

Examples of telepresence include undersea work to repair pipelines and cabling system. Deep water diving is risky and costly, so telepresence systems can prove cheaper as well as