Developing J2ME games
Razum d.o.o.
Gozdna pot 7
1000 Ljubljana
for mobile phones
Slovenia
www.razum.eu
info@razum.eu
Žiga Hajduković, Razum d.o.o.

Razum d.o.o.
Gozdna pot 7
1000 Ljubljana
Slovenia
www.razum.eu
info@razum.eu
DEVELOPING J2ME GAMES FOR MOBILE PHONES
 Intro
 Mobile devices
 Mobile games
 HOWTO: Pong!
 The Future
 Questions / Contact
 The Little Red Riding Hood

Razum d.o.o.
Gozdna pot 7
1000 Ljubljana
Slovenia
www.razum.eu
info@razum.eu
INTRO
 Razum, research and development studio → www.razum.eu
Developing advanced solutions to interesting problems and researching new technologies
 Platform for building enterprise information systems
 Server + web + mobile Blackberry client
 Client-server Application Architecture Design
 Oystar Small Business Loyalty – RFID, Nokia 6131 NFC - 1st European NFC Competition → Award!
 Mobile games
 6-week “Mobile Game Development” course
Faculty for computer and information science, University of Ljubljana
6 lessons, 2 groups, 60 students, game dev. competition w/ awards!
 Cocoasoft, Mobile Game Design & Development, AI
Car Racer 2 (racing FRP), Pahtum (board game, AI), Michel Vaillant Rally ..
 Tetris1D.org → www.tetris1d.org
Tetris1D, Tetris1D Mobile Edition, Twinoo, Trioomph ..

Razum d.o.o.
Gozdna pot 7
1000 Ljubljana
Slovenia
www.razum.eu
info@razum.eu
MOBILE DEVICES - SHOUJI ( 手机 )

Mobile phones

X1 / Windows Mobile / iPhone / Blackberry Storm ..

Razum d.o.o.
Gozdna pot 7
1000 Ljubljana
Slovenia
www.razum.eu
info@razum.eu
MOBILE DEVICES - ADVANCED MULTIMEDIA FUNCTIONS

Walkman - MP3 / Radio

Photo / Video camera

Television

GPS

Internet / blogging device

Razum d.o.o.
Gozdna pot 7
1000 Ljubljana
Slovenia
www.razum.eu
info@razum.eu
MOBILE DEVICES

3.3 billion (November, 2007) mobile phones – half of the world population (80% by 2013)

Keys, wallet, phone

Wallet → phone (!)

Keys → phone (!)

Connecting people, social interaction

Relatively cheap but high tech.

The transition: Family phone → personal object!

Clock, alarms (wake up, events, todo..), calendar, camera

Navigation, GPS, Bluetooth, ..
en.wikipedia.org/wiki/Mobile_phone

Mobile Gaming!
revenue (billion $) (~10% annual growth): 2007 => $3.9, 2008 ~>$4.5, 2011 ~> $6.3

Razum d.o.o.
Gozdna pot 7
1000 Ljubljana
Slovenia
www.razum.eu
info@razum.eu
MOBILE DEVICES - PROPERTIES

Good +

Connectivity – “always” connected

Handy – always nearby

Personalized – personal device

Evil -

Unpredictable costs – of connecting (but improving..)

Unpractical – small screen, small keypad

Razum d.o.o.
Gozdna pot 7
1000 Ljubljana
Slovenia
www.razum.eu
info@razum.eu
MOBILE GAMES – MOBILE INTERFACE DESIGN GUIDELINES

Quality function formula:
 Design for a tiny screen with bad contrast and color quality
 MIN( user input ) - input is generally annoying for the user
 MIN( data transfer ) - GPRS → $/Kb
 MIN( processor usage ) - battery! (3D?..)

Keep in mind, desktop computer vs. mobile device paradigms
 big screen broadband VS small screen GPRS
 browse the web VS require specific piece of info

Razum d.o.o.
Gozdna pot 7
1000 Ljubljana
Slovenia
www.razum.eu
info@razum.eu
MOBILE GAMES – DEVELOPMENT PLATFORMS

Java 2 ME
MIDP (1.0, 2.0, 2.1, ..3.0), CLDC (1.0, 1.1)
Extensions/JSRs: Bluetooth, WMA, MMAPI, PIM, Location, 3D..

Symbian / C++

Python (Nokia S60 platform)

BREW (US) / C++ / Qualcomm

i-Appli (Japan) ~ J2ME / DoCoMo

Android (Google, Linux)

iPhone!

.NET Compact Framework (PocketPC, Windows Mobile)
en.wikipedia.org/wiki/Mobile_development

Razum d.o.o.
Gozdna pot 7
1000 Ljubljana
Slovenia
www.razum.eu
info@razum.eu
MOBILE GAMES – J2ME

Why Java?

Widely supported on mobile phones and devices

Development tools readily available and free (Netbeanse, Eclipse, ..)

Strong developer community

MIDlet – the mobile applet

MIDlet installation package – JAR+JAD files

MIDP 1.0 .. LCD UI, RMS ..

MIDP 2.0 .. Game API, MultiMedia API, setFullScreenMode

CLDC 1.0 .. J2SE subset .. java.util, java.lang

CLDC 1.1 .. +floating point..

Razum d.o.o.
Gozdna pot 7
1000 Ljubljana
Slovenia
www.razum.eu
info@razum.eu
MOBILE GAMES – J2ME API, OPTIONAL PACKAGES, MSA 2.0

Razum d.o.o.
Gozdna pot 7
1000 Ljubljana
Slovenia
www.razum.eu
info@razum.eu
MOBILE GAMES – TYPICAL DEVELOPMENT PROCESS – INIT
 Brain storming
The all important phase, more so as a game project begins, reappearing during various stages of
development.
 Game Design Overview Document
Usually a quick brain dump of an individual to present a new game idea, couple of pages, core
gameplay description, main characters and game objects, and approximate development time line.
 Game Design Document
Nice to have to keep all the developers on the same page, descriptions of all the game elements:
obstacles, opponents, NPCs, AI, level design, story flow.. depending on the game type

Razum d.o.o.
Gozdna pot 7
1000 Ljubljana
Slovenia
www.razum.eu
info@razum.eu
MOBILE GAMES – TYPICAL DEVELOPMENT PROCESS – ITERATION
 Development (coding, graphics, sound)
Tight developer coordination with graphics and audio designers
 Iterative “gameplay testing ←→ development” cycle
The QA “department” should test the game as often as possible!
 Iterative “Porting ← Testing → Bugfixing” cycle
adjustments and optimizations for actual specified devices
 Release
woohoo!

Razum d.o.o.
Gozdna pot 7
1000 Ljubljana
Slovenia
www.razum.eu
info@razum.eu
HOWTO: PONG!

Game Engine

HOWTO: Pong!

Live Test!

Tools
Netbeans 6.1 + Mobility Pack
Sun Java Wireless Toolkit (2.5.2 for CLDC)

Razum d.o.o.
Gozdna pot 7
1000 Ljubljana
Slovenia
www.razum.eu
info@razum.eu

Razum d.o.o.
Gozdna pot 7
1000 Ljubljana
Slovenia
www.razum.eu
info@razum.eu
MOBILE GAMES – TIPS AND TRICKS

Graphics

Contrast! Outlining sprites and game objects

Transparency for non-rectangular sprites

Automatically (PNG optimizers: pngout..) and manually lower number of colors and edges

Optimization

Speed (WTK Profiler helps)

Memory (Heap) – prevent fragmentation!

Package size (JAR Size) ... pngout, no folders, short class names, lower number of files

Obfuscation

Speed “sense“

Aliveness – is it working? Use indicators, progress bars..

Responsiveness – How much lag is there between user action and game screen response?

Masking delays – Use splash images while loading.. mini games when searching for open games..

Porting

Detecting and adjusting to screen size

Netbeans mobile “configurations“

Vector graphics (simple lines and rectangles or even more complex like SVG API (not yet widely supported!))

Razum d.o.o.
Gozdna pot 7
1000 Ljubljana
Slovenia
www.razum.eu
info@razum.eu
THE FUTURE (IS NOW!)

3G → 4G (Kb/s → Mb/s)
streaming video, music downloads, (file sharing?)

folding e-paper, built-in projectors

barcode → URL (barcode = RFID! =..= snapshot? (tamagochi feeding..))

NFC API – Nokia 6131 NFC, (Oystar..)

localized search .. GPS .. (restaurants, hotels..)

GPRS → WiFi, UMTS → HSDPA → 4G ..

battery → fuel cell

mobile payment (NFC, Felica, m-Pay (Moneta..))

implants!? (tooth!, ear, fingers?..)

Razum d.o.o.
Gozdna pot 7
1000 Ljubljana
Slovenia
www.razum.eu
info@razum.eu
LINKS
 Mobile game development course, spring 2005 (in Slovenian only)
www.tetris1d.org/game/dev/tecaj/Lesson_01.php
 Gamasutra → www.gamasutra.com
 Game Developers Conference (Mobile) → www.gdconf.com
 Games on Deck → www.gamesondeck.com
 Forum Nokia → forum.nokia.com
 Sony Ericsson Developer → developer.sonyericsson.com
 About Mobility Weblog – C. Enrique Ortiz → weblog.cenriqueortiz.com
 Sun Mobility → developers.sun.com/mobility/allarticles/
 Gameloft → www.gameloft.com
 glu → www.glu.com
 EA Mobile, Pop Cap, THQ Wireless ..
 Google → www.google.com

Razum d.o.o.
Gozdna pot 7
1000 Ljubljana
Slovenia
www.razum.eu
info@razum.eu
THE LITTLE RED RIDING HOOD – TECHNOLOGY PREVIEW
Mobile download: m.razum.si
web demo: www.razum.si/game/
 Player decision controlled story flow engine
 “Choose Your Own Adventure“ style interactive gameplay
 Vector graphics engine
 All graphics scalable to different screen sizes!
(one size fits all)

Razum d.o.o.
Gozdna pot 7
1000 Ljubljana
Slovenia
www.razum.eu
info@razum.eu
QUESTIONS?

Contact

Žiga Hajduković
ziga.hajdukovic@razum.eu
 Looking for a fresh new job?

Razum, research and development studio
info@razum.eu
www.razum.eu