Transcript Mobile Gaming

CS5961: Networked
Game Design
Introduction to Mobile Gaming
CS 5961: Networked Game Design
Lecture 13
Mobile Gaming

(One of the?) fastest growing segments of game
industry
– Mobile consoles (e.g., PSP, N-Gage, Nintendo DS)
– Mobile phones

Unique challenges
– Constrained I/O (small screens, limited/slow input devices)
– Power-constrained (battery life issues)
– Wireless networks (slow, unreliable, power-hungry)

Unique opportunities
– Cell phone market >> game console market
– Opportunities to exploit “real” social interaction
– Location-based games
CS 5961: Networked Game Design
Lecture 13
Common Mobile Game Genres

Standalone
– Miniature version of console/PC games  non-interactive
– Often “casual” games (e.g., Tetris)  very popular with women

Multi-player
– Typically head-to-head or small groups
– Conventional games vs real-time trivia (e.g., sporting events)

Location-based / “mixed reality” / “alternate reality”
– Exploit presence of GPS in modern phones
– Harder to determine “location” for generic wireless (triangulation)
– Ex.: GeoCaching, PacManhattan, Can You Find Me Now?

Social games / interaction-based
– Virtual love, digital clubs, share w/ friends
– E.g., Avapeeps (Digital Chocolate)  date other people’s avatars
CS 5961: Networked Game Design
Lecture 13
Hardware Platforms

Mobile consoles
– PSP, N-Gage, Nintendo DS
– 300+MHz cpu, vector unit, FPU
– 32MB+ embedded DRAM/Flash
– Display: 480x762 (PSP), 256x192 (DS)
– Support for 3D graphics/sound
– 802.11, USB, game inputs

Cell phones
– Weak cpu, special cell circuits
– 12MB DRAM (RAZR), 32MB (Sidekick)
– Display: 176x220 (RAZR), 240x160 (SK)
– Usually no 3D graphics support
– SMS, 3G, Bluetooth
CS 5961: Networked Game Design
Lecture 13
Development Platforms

J2ME (Java 2 Micro Edition)
– Seems to be dominant software platform
– Portable across many hardware platforms
» Pretty much every cell phone has J2ME
– “Not most powerful or pretty, but pervasive”

BREW (Qualcomm)
– Popular in the US (less so abroad)
– Better support for 3D graphics and sound

Symbian OS (Nokia)
– Powerful OS/platform for high-end phones
– Typically more expensive games

ExEn, PalmOS, DoJa, WIPI, …
CS 5961: Networked Game Design
Lecture 13
Common Limitations

Low processing power & small screens
– Need to count on good game play over flashy graphics
– No uber powerful game AIs or high res 3D graphics

Limited sales channels  typically cell providers
– Hard to market games  tend to rely on well known IP/genres

Wireless communications
– Limited wide-area bandwidth, lossy, unstable
– Depending on technology, not pervasive (802.11/Bluetooth vs 3G)

Limited location accuracy
– GPS is pretty good, but only to ~20meters (outside ok, inside not)

Proliferation of heterogeneous devices
– Need to design for lowest common denominator
CS 5961: Networked Game Design
Lecture 13
Technology Issues
CS 5961: Networked Game Design
Lecture 13
Technical Challenges

Low-res displays

Weak processors

Small memory/storage capacity (no VM)
– Example: BREW could only access 200 bytes of dynamic data (2002)

Severe power constraints

Wireless/mobile networking issues
CS 5961: Networked Game Design
Lecture 13
Power-Aware Computing

Mobile devices have limited battery power

Major power consumers:
– Display / backlighting
– Wireless network
– “Vibrate”
– CPU / memory

Q: What kinds of things can you do to preserve
power?
– Discuss
– Turn off units (disks, displays, network, …) when not being used
– Voltage scaling (often available in mobile processors)
– Power-aware scheduling (OS or app-based)
CS 5961: Networked Game Design
Lecture 13
Wireless Networks

Wide range of wireless technologies
– Bluetooth (802.15): “personal area network”
– IRDA: short range, point-to-point
– 802.11: wireless LAN (variety of bandwidths and ranges)
» 802.11b: 2.4GHz (shared), 11 Mbps, ~300 feet indoor range
» 802.11g: 2.4GHz (shared), 11/54 Mbps, ~300 feet indoor range
– SMS: cell phone messaging (160 bytes max, 4+ sec latency)
– 2G/3G: high bandwidth digital cell based
– WiMAX: wireless MANs (802.11 on steroids)

Access points versus ad hoc

Security (WEP, authentication, encryption, …)
CS 5961: Networked Game Design
Lecture 13
Cellular Network Topology
Base Station (BS)
Internet
Fixed Host (FH)
Wireless Cell
CS 5961: Networked Game Design
Lecture 13
Wireless Challenges

High bit error rates
– Congestion (shared channels, data corruption, …)

Asymmetric channels
– Bandwidth asymmetry
– Differing latencies

High delays (compared to wired networks)
– Channel reservation  “slots”
– Transceivers often go into “sleep” mode for power savings
CS 5961: Networked Game Design
Lecture 13
Programming Embedded Devices

Programming for small memory footprints
– Limited stack size  must have predictable maximum size
– Compressed data  adds to compute overhead
– Overlays  careful memory management
– Memory allocation tools (manage different “flavors” of memory)

Need predictable execution times
– Similar to “30Hz frame update” cycle
– Must do it in the face of disabled I/O devices (radio, display, …)

See Regehr’s Embedded System course for details
CS 5961: Networked Game Design
Lecture 13
Location Tracking Technologies

GPS:
– Typical accuracy is 15 meters
– Signal can be disrupted by other electromagnetic radiation
– Limited effectiveness inside buildings (metal blocks signals)

WLAN triangulation:
– Typical accuracy is 1-5 meters  but high variance
– Requires multiple WLAN access points to triangulate signal power
– Somewhat effective indoors
– Multipath problems (reflections, signal loss)

RFID:
– Can be highly accurate (under 1 meter), but very short range
– Increasingly common and available
CS 5961: Networked Game Design
Lecture 13
Getting Started

Develop on software emulators
– SDK/emulators typically free

BREW
toolkit
Getting certified for deployment can
cost a couple thousand dollars
– Need to test for compatibility & safety

To actually sell your game:
– Need to partner with carriers (typical)…
– … or market via web to “expert users”
J2ME
toolkit
– Most cell users have no clue how to
download and install applications
CS 5961: Networked Game Design
Lecture 13
Possible Future Developments

Growth of interactive / “alternate reality” games
– Example: PacManhattan (NYU)
» Five players on the street, five in a control room
» Simple (cell voice based), but effective
– Successfully used as a form of viral marketing

Wearable computing
– Computer is always with you  unobtrusive as clothing
– Hands-free use, many sensors, embedded in real world
CS 5961: Networked Game Design
Lecture 13
“10 Hot Trends in Mobile Gaming”
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Advertising-supported games
Direct-to-consumer
Next generation N-Gage
More connectivity and multiplayer
Tetris will sell millions of downloads
More crossover with Web and online gaming
3D gaming will take off (handheld consoles)
Flash Lite will make an impact
Mobile game audio finally gets some props
More camera and location-based games
Ref: http://www.pocketgamer.co.uk/r/Mobile/feature.asp?c=2075
CS 5961: Networked Game Design
Lecture 13