Getting Started in Android Game Development

If you're interested in developing a game for the Android platform, there is a lot you need to know.  I'm the developer of Light Racer, Light Racer 3D, Antigen, Deadly Chambers and Wixel, which are currently available on the Android Market. I've also been involved with the development of about 5 other games for Android and iOS and am co-author of Beginning Android Games 2nd Edition.  I've developed games before but the original Light Racer was my first Android application and I learned quite a bit about writing Android games that I'd like to share with everyone.  I even wrote an online book detailing the development of Light Racer 3D, which is full of how-tos and useful code snippets. If you have previous experience with game development, moving over to the mobile platform won't be all that difficult.  You will mostly just need to learn the architecture and API.  If you're new to game development, I have assembled a list of must-knows for getting started.  They apply to many different types of games, including action, strategy, simulation and puzzle.

Android is a Java-based environment.  This is nice for new developers as Java is widely accepted as a much easier language to get started in than C++, which is the norm for mobile development and is what I use now.  Google has also done an excellent job with documenting the API and providing examples to use.  There is an example to show functionality for almost 100% of the API, called API Demos.  If you're familiar with Java and have already used Eclipse, getting your first app working should be fairly simple.  If you've never coded anything in your life before, you will have a lot to absorb as you move forward, but don't get discouraged. If you have some experience and are wanting to develop a cross-platform game or high-performance Android game in C++, check out BatteryTech, which is a platform I wrote and am currently using for game development.

Get the SDK

The first step in getting started with the Android platform is to get the Android SDK (Software Development Kit).  The SDK has the core libraries, an emulator, tools and sample code.  I highly recommend using Eclipse and the android eclipse plugin.  Eclipse IDE for Java Developers is fine if you are just doing Android.  If this is your first Java development project, you will want to download the full Java SE Development Kit (JDK) as it contains tools you will need for signing and deploying your application.

Learn the application architecture

As tempting as it may seem to just dive right in, it's very important to understand the android application architecture.  If you don't learn it, you may design things in such a way that will make it very difficult to fix problems with your game down the line.  You will want to understand Applications, Activities, Intents and how they are all related to each other.  Google has provided good information on the architecture here.  The really important thing is to understand why your game may need to consist of more than one Activity and what that means to designing a game with good user experience.  This is where things tie in to the Activity lifecycle.

Learn the activity lifecycle

The activity lifecycle is managed by the Android OS.  Your activity will be created, resumed, paused and destroyed as the OS dictates.  Handling these events correctly is very important to having an application that behaves well and does what the user perceives as correct.  It's very good to know how all of this works before you start designing your game because you will save yourself debugging time and costly redesign time later on.  For most applications, the default settings will work but for games, you may want to consider turning the SingleInstance flag on.  When set as default, android will create new instances of the activity as it sees fit.  For a game, you may only want to have 1 instance of the game activity.  This has some implications for how you need to manage the state of things but for me it solved some resource management issues and it should be considered.

The main loop

Depending on what type of game you are writing, you may or may not have a main loop.  If your game is not time-dependent or if it only responds to what the user does and will wait forever for user input without making any kind of visual changes, you may not need a main loop.  If you are writing an action game or a game that has animations, timers or any kind of automation, you should seriously consider using a main loop.

The main loop of a game is the part that "ticks" sub systems in a specific order and usually as many times per second as possible.  Your main loop will need to run on its own thread.  The reason for this is that Android has a main UI thread and if you don't run your own thread, the UI thread will be blocked by your game which will cause the Android OS to not be able to handle any of its normal update tasks. The order of execution is usually as follows:  State, Input, AI, Physics, Animation, Sound and Video. 

Updating State means to manage state transitions, such as a game over, character select or next level.  Often times you will want to wait a few seconds on a state and the State management is the part that should handle this delay and setting the next state after the time has passed.

Input is any key, scroll or touch from the user.  It's important to handle this before processing Physics because often times input will affect the physics so processing input first will make the game more responsive.  In Android, the input events come in from the main UI thread and so you must code to buffer the input so that your main loop can pick it up when the time comes.  This is not a difficult task.  Defining a field for the next user input and having the onKeyPressed or onTouchEvent set the next user action into that field is all that will be required.  All the Input update needs to do at that point is determine if it is valid input given the state of the game and let the Physics side handle responding to it. 

The AI update is analagous to a user deciding what they are going to "press" next.  Learning how to write AI is out of the scope of this article but the general idea is that the AI will press buttons just like the user does.  This will also be picked up and responded to by the Physics update.

The Physics update may or may not be actual physics.  For action games, the point of it is to take into account the last time it was updated, the current time it is being updated at, the user input and the AI input and determine where everything needs to be and whether any collisions have occured.  For a game where you visually grab pieces and slide them around, it will be the part that is sliding the piece or letting it drop into place.  For a trivia game, it would be the part deciding if the answer is right or wrong.  You may name yours something else, but every game has a part that is the red meat of the game engine and for this article, I'm referring to it as Physics.

Animations aren't as simple as just putting an animated gif into your game.  You will need to have the game draw each frame at the right time.  It's not as difficult as it sounds.  Keeping state fields like isDancing, danceFrame and lastDanceFrameTime allows for the Animation update to determine if its time to switch to the next frame.  That's all the animation update really does.  Actually displaying the change of animation is handled by the video update.
 
The Sound update handles triggering sounds, stopping sounds, changing volumes and changing the pitch of sounds.  Normally when writing a game, the sound update would actually produce a stream of bytes to be delivered to the sound buffer but Android manages its own sounds so your options for games are to use SoundPool or MediaPlayer.  They are both a little sensitive but know that because of some low level implementation details, small, low bitrate OGGs will yield the best performance results and the best stability.

The Video update takes into account the state of the game, the positions of players, scores, statuses, etc and draws everything to screen.  If using a main loop, you will want to use the SurfaceView and do a "push" draw.  With other views, the view itself will call the draw operation and the main loop won't have to do it.  SurfaceView gives the highest frames per second and is the most appropriate for games with animation or moving parts on screen.  All the video update should do is take the state of the game and draw it for this instance in time.  Any other automation is better handled by a different update task.

What's this code look like?  Here's an example.

public void run() {
    while (isRunning) {
        while (isPaused && isRunning) {
            sleep(100);
        }
        update();
    }
}

private void update() {
    updateState();
    updateInput();
    updateAI();
    updatePhysics();
    updateAnimations();
    updateSound();
    updateVideo();
}


3D or 2D?

Before you start on your game, you need to decide if you're going to go 3D or 2D.  2D games have a much lower learning curve and generally are easier to get good performance on.  3D games require much more in-depth math skills and may have performance issues if you are not very careful.  They also require the ability to use modeling tools like 3D Studio and Maya if you intend to have shapes more complex than Boxes and Circles.  Android supports OpenGL for 3D programming and there are many good tutorials on OpenGL that one can find to learn it.

Build simple, high quality methods

When getting started, make sure that you avoid writing one big long monolithic method that is "the game."  If you follow the main loop pattern that I described above, this should be fairly easy.  Each method you write should accomplish one very specific task and it should do so error-free.  For example, if you need to shuffle a deck of cards, you should have a method called "shuffleCards" and that should be all it does. 

This is a coding practice that applies to all software development but it's particularly important in game development.  Debugging can get very difficult in a stateful, real-time system.  Keep your methods small and the general rule of thumb is that each method should have 1 and only 1 purpose.  If you're going to programatically draw a background for a scene, you may want a method called "drawBackground."  Things like that will make it so that you develop your game in terms of building blocks and you will continue to be able to add what you need without making it too complex to understand.
 
It's all about efficiency!

Performance is a major issue for any game.  The goal is to make the game as responsive as possible and to also look as smooth as possible.  Certain methods like Canvas.drawLine are going to be slow.  Also drawing an entire screen-sized bitmap onto the main canvas every frame will also be costly.  Balancing things like that is necessary to achieve the best performance.  Make sure to manage your resources well and use tricks to use the least amount of CPU to achieve your task.  Even the best game will not be very fun if it can't perform well.  People in general have little tolerance for choppiness or poor response.

Tips and Tricks

Take a look at the example for LunarLander in the SDK.  It uses a SurfaceView and that would be the appropriate view to use for a game that needs the highest number of frames per second possible.  If you're going 3D, take a look at GLSurfaceView. It takes care of the OpenGL device initialization and provides a mechanism for rendering.  For LightRacer, I had to optimize the way I have everything drawn or else the framerate would be drastically lower.  I drew the background to a Bitmap only once which was when the view is initialized.  The light trails are in their own bitmap which gets updated as the racers move.  Those two bitmaps are drawn to the main canvas every frame with the racers drawn on top and then finally an explosion.  This technique made the game run at a playable rate.

It's also a good practice to have your bitmaps be the exact size you intend to draw them on screen, if applicable.  This makes it so that no scaling is needed and will save some CPU.

Use a consistent Bitmap Configuration (like RGBA8888) throughout the game.  This will save the graphics library CPU in having to translate the different formats.

If you're determined to develop a 3D game but have no 3D knowledge, you will want to pick up a book or two on 3D game programming and study up on linear algebra.  At a bare minimum, you must understand dot products, cross products, vectors, unit vectors, normals, matrixes and translation.  The best book I have come across for this math is called Mathematics for 3D Game Programming and Computer Graphics.

Keep the sound small and at a low bitrate.  The less there is to load, the faster loading times will be and the less memory the game will use.

Use OGGs for sound, PNGs for graphics.

Make sure to release all media players and null out all of your resources when the activity is destroyed.  This will ensure that the garbage collector gets to everything and that you don't have any memory leaks between launches of the game.

Join the Android Google group and find community support.  There will be people that can help you along the way.

Above all, spend time testing and retesting and making sure that every little thing works exactly the way you would expect it to.  Polishing the game up is the longest and hardest part of development.  If you rush it out to market, you will probably have a disappointed crowd and you may feel that all your hard work is wasted.  It's not possible to have 100% of people love what you write but you should at least try to put out the highest quality work that you can.

Google has excellent documentation for getting started here.

Find working game code samples and how-tos in the Light Racer 3D Development Journal

Need a book recommendation? Try Beginning Android Games 2nd Edition by Mario Zechner and Myself (Author of libgdx and friend of mine).

Finally, Battery Powered Games offers pro Android (and iOS) game development consulting services so if your company has a need to contract out mobile game development, that's the place to go!

160 Comments

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I am looking for this

I am looking for this information for my Android Developers team specially for Jr and Freshers...

heyy

i agree with u

A good article

A good article on android game programming.

Good article on adroid game programming

Thanks for such great article.

Great Article. I'm looking to

Great Article. I'm looking to get into Android Game Programming and just started reading random articles. This one provided a lot of inspiration!

Portable

Is it possible to have all this programs as portable?

Very helpful article for

Very helpful article for starting game development in Android. Now I got inspiration to try samples for game.

Apple computer

Hi Robert,
Thanks a lot for your great article. I am new to this and am trying to get the whole picture. I will start on android but I would like to be able to code for multiple devices. Is there a way to develop for iPad without having to buy an Apple computer? If I still need one, can I at least code and test on my pc before getting it to the app store?

BatteryTech (I assume that's

BatteryTech (I assume that's what you're referring to) is very different than Sencha Touch. The approach is totally different. For BT, you write your game in C++ (or lua as we do) and compile natively to the platform which makes it very well suited for high performance games. ST uses HTML5 and is probably better suited to cross-platform applications. The short answer is that you can probably use them together but much fiddling will be required. This assumes ST outputs an Android project and an XCode project so you can merge the BatteryTech parts in and somehow init the GLView of BatteryTech from Sencha Touch on both platforms, which is how you enter it on a mobile device. I've never done it so I can't really say.

Part of a bigger app

Hi Robert. I am working on a project and am researching multiple platforms like Sencha Touch and BatteryPowered Games to see what I can use. My question is can BatteryPowered Games can be used with Sencha Touch to make one bigger application that has multiple aspects?

hi

hello robert..i love to make mobile games..but i do no how to start and what to learn..so can you guide me plz??? :( just tell me what i have to learn first....:(

Thank You

Thank you for such good information on android development!

Hi Jesse, Follow the links on

Hi Jesse,

Follow the links on the "SDK" paragraph and you should be able to find everything you need. Java, Eclipse, Android SDK and ADT (installed via Eclipse) should get you started.

Hi Robert, To be honest i'm

Hi Robert,

To be honest i'm having a hard time finding out what SDK, software, programs etc. i need to download, can you explain?

BatteryTech

Hi Sean,

It does work for other applications but the big thing to understand about it is that it has a self-contained UI system build for OpenGL ES, which works great for 99% of games but may not work well enough for some apps which require heavier user interface. It all depends on what you want to do - it's pretty great for everything we've done so far.

If you have a question about a specific application of BatteryTech, I'll be happy to answer it. Please feel free to contact me!

BatteryTech

Hi Robert,
Like so many others I want to thank you for this post and all of it's valuable content. I think BatteryTech is an amazing framework I just have one question. Obviously it is focused on multi-platform development for games but I was wondering if it works just as well for other applications?

Thanks again,
Sean

Tyler, You'll still need an

Tyler,

You'll still need an IDE. BatteryTech is a software library - it just gives you an easy C++ API to access everything in the different targets universally. You still need the toolchains, such as either VS or Eclipse/CDT/MinGW in Windows and XCode for Apple dev. I use both VS and Eclipse/CDT in Windows 7 64 with BatteryTech with no issues. It's not a library for total beginners but if you're comfortable with the idea of C++ game development and want to save 6 months of cross-platform programming, it'll do the trick :)

re: This is why I developed

Thank you for the prompt response! So if I was to go the route of getting BatteryTech, all I would need in addition to BatteryTech is the Android SDK and Android NDK? Or will I still need to get something like Microsoft Visual C++ as an IDE... And I'll be doing this on a 64-bit version of Windows7, any problems there?

This is why I developed

This is why I developed BatteryTech :)

You can write C++ for Android but you'll still need the Android SDK and Android NDK to build and test. When testing in Windows, you can either test on an emulator (yuk, I hate running on an emulator) or you can have your code build for Windows, which requires several considerations and will lead you once again to a library like BatteryTech. Same goes for iOS/OSX.

If you're ok with using Java, you'll only need the Android SDK, Eclipse and the ADT plugin.

the basics

I'm having a difficult time trying to understand what exactly is all required to make an android game on a PC. From my understanding I need to get an IDE where I will do the actual coding. I will also need an SDK that will assist in making the game by giving me libraries and such. I would like to make a game on my PC, and am just trying to figure out what I'll need. I did some Java quite a few years back but I dont remember much, I would much rather program in C++. I was reading that I could probably use Microsoft Visual C++ as the IDE and then I'd need to pick out an SDK that uses C++ and is for Android. Am I even close? And how different is what I would need for making an iphone game on a PC compared to making an Android game on a PC? I would really appreciate any help! Information on all this seems so scattered and random.

Thanks

Thanks for the great article

THANKS

Thanks for this article.

RE: Animation studio

Hi Riya,
My name is Surya.
Where are you planning to open the studio? I would recommend Bangalore or Hyderabad because ( I am from Hyderabad ) there are already many animation training institutes over there so when ever you would need more people to help you out with stuff you can easily find someone. Keep in mind that the commercial capital of India is Mumbai and the the capital of India is Delhi. Bangalore would be my preferred choice because of the nice climate along with other reasons.
all the best
Surya

Hi, Iam Arun from india. Iam

Hi, Iam Arun from india. Iam working as rigging artist in an animation studio for last 10 years. Already we have a small team here. if you would like to start an animation studio in india , i can help you. my email id is arunpillaii@gmail.com

best reagrds.
Arun.S

Thanks for this article

Thanks for this article

Set up an Animation Studio in India

Hi there,
I am an American. I desire to Setup an Animation Studio in India. At present i'm looking for artists. I picked India for the reason that it is more inexpensive when compared with U.S. I want to fully understand the strategies for starting a business in India, specifically an animation studio.

Could you guys please help me out?

Cheers!

Simple and straight to the point! Excellent guide - defo a bookmark!

My recommendation - either

Joshua,

My recommendation - either learn how to develop games and go for it or put together a good game design doc and pitch it under NDA to game dev groups that you think can do a good job at it. You can get a percentage of royalties for it as a deal.

2D Game Concept - Plz Help. :)

I'll keep this short. I've been playin PC games of one type or another for
almost 30 years. I'm a computer tech, I know software, hardware and even
understand programing, at least enough to know i hate it. The problem is,
I have a freakin killer game concept and it needs to be made! The public dont
deserve to suffer without it anymore. *grin*

I was just hoping maybe you could help Mr. Robert Green.
Or maybe point me in the direction of other developers? :)

Thanks either way.
-Josh

I develop everything in C++

I develop everything in C++ now. I target both Android and iPhone with the same codebase (using BatteryTech). I believe C++ is a better language for games in design, performance and portability.

You can teach yourself anything in the world if you're motivated, but going to school for CS will give you a boost on many things you'll need to understand to be a good game developer.

I'm glad you find this all useful! I try to write when I can.

Cheers