When creating a build of your game for Amazon Underground, it’s important to make sure that your APK has a unique bundle identifier and an icon with the Underground sash. These two requirements help make your Underground game stand out when installed on a player’s device and also help avoid any installation conflict you may have with the paid version of your game. You can learn more about these requirements from our dev portal here. If you are building a Unity Game, you already know that there isn’t an easy way to create separate Android builds per target. Once you configure the build, it's the same for all Android platforms. To get around this, we are going to talk about a plugin called Advanced Builder which will help you not only automate your different builds but also allows you to write a custom build script to change out icons based on whether it’s an Underground version or a standard one. Let’s get started.

Advanced Builder

Advanced Builder is paid plugin on the Unity Asset store that allows you to set up individual builds based on target platforms and automate a lot of the tedious build steps. Once you have it installed you can create a new release type for the Underground build. Here you can see I have a Standard build and my Underground Build.

One thing to note is that each release type has its own bundle identifier.

Next, setting up a build for the Amazon Appstore is as easy as checking Amazon Store in the Distribution platforms area.

Also, you can set each of the Android Architectures individually. Since Amazon devices are ARMv7 compatible I don’t do builds for FAT or x86.

Once you have everything setup, you can create your individual builds for the Amazon Appstore, Underground and any other platforms you distribute your game on.

Before we do the build, we are going to want to create a custom build script that lets us swap out the icons based on the release type.

Creating a Custom Script

Advanced Builder allows you to set custom C# scripts that run logic before and after the build. To make one, create an Editor folder in your project and add a new C# class to it. You’ll want to also make that class implement the IAdvancedCustomBuild interface. There are two methods you’ll need to add:

public void OnPreBuild(Configuration configuration, System.DateTime buildDate)

{

}

public void OnPostBuild(Configuration configuration, System.DateTime buildDate)

{

}

Once you have the script in your project, add it to Advanced Builder’s Custom Settings.

From here we will create a method that looks at the current build, gets the icons from that platform and loads them from a target folder. You’ll need a property at the top of your class that points to where your icons will be stored:

public const string ICON_PATH = "Assets/DragonSweeper/Artwork/Icons/";

Next we’ll need a way to convert the BuildTarget supplied by Advanced Builder into a BuildTargetGroup to use with the PlayerSettingsClass. Add the following static method:

public static BuildTargetGroup ConvertToGroup(BuildTarget buildTarget)

{

    BuildTargetGroup targetGroup = BuildTargetGroup.Unknown;

    switch (buildTarget)

    {

        case BuildTarget.Android:

            targetGroup = BuildTargetGroup.Android;

            break;

        default:

            throw new ArgumentOutOfRangeException("buildTarget");

    }

    return targetGroup;

}

Unity supports a lot of different platforms so simply add a new case based on the ones your game will target. Here, I am simply supporting Android.

Now we need to find all the icons size for a specific platform. Create the following method:

private static void AssignPlayerSettingsIcons(BuildTarget target, ReleaseType releaseType)

{

    var targetGroup = ConvertToGroup(target);

    int[] iconSizeArray = PlayerSettings.GetIconSizesForTargetGroup(targetGroup);

    Texture2D[] iconArray = new Texture2D[iconSizeArray.Length];

    for (int i = 0; i < iconSizeArray.Length; i++)

    {

        var path = ICON_PATH + releaseType.name + "/icon-" + iconSizeArray[i] + ".png";

        Debug.Log("Icon Path "+ path)

        Texture2D iconTexture = AssetDatabase.LoadAssetAtPath(path, typeof(Texture2D)) as Texture2D;

        if (iconTexture != null)

        {

            iconArray[i] = iconTexture;

        }

        else

        {

            Debug.LogError("Error, could not find icon with size : " + iconSizeArray[i]);

        }

    }

    PlayerSettings.SetIconsForTargetGroup(targetGroup, iconArray);

}

As you can see, we generate out a unique path to each icon based on the name of the release in Advanced Builder. We push that path into an array that Unity will use to package up the game with. The final thing we need to do is call this method in OnPreBuild and pass in the values it needs:

public void OnPreBuild(Configuration configuration, System.DateTime buildDate)

{

   AssignPlayerSettingsIcons(configuration.platformArchitecture.buildTarget, configuration.releaseType);

}

Now our custom build script is ready. We just need to create the icons and put them in the correct folder.

Creating Icons

Your Underground game will need to use a custom sash. You can find out more about this here. I’ve gone ahead and created icons for Android’s 6 sizes (192, 144, 96, 72, 48 and 36) with the Underground sash template.

I also have the same icons for my standard build and I put both of them in my Asset folder.

Now when we run our builds, Advanced Builder will include the right icons for my standard and Underground APK.

Conclusion

After we do our build, you’ll now have folder for each APK. Here you can see the Amazon Store folder contains our standard and Underground APKs.

You can always do a quick test to make sure this worked by turning the .apk into a .zip, unzipping it and looking at the icons in the resources folder.

And that’s it! Now you can easily create your Underground builds from the same project and leverage your existing codebase.

What Is Amazon Underground?

Amazon Underground is a new app for Android phones. It has all of the functionality of our regular Amazon mobile shopping app, plus an exciting addition: more than twenty thousand dollars in apps, games, and in-app items that are 100% free for customers. For you app developers, Amazon Underground includes a new monetization model where Amazon pays you based on the amount of time your app is used. With Amazon Underground, you can turn 100% of your Android users into revenue-generating customers.

To learn more about Amazon Underground and the Amazon Appstore be sure to check out the following links.

• Register for a free developer account
• Learn more about Underground
• Make the Amazon Appstore Your Game’s Home

- Jesse Freeman (@jessefreeman)

You’ve built a great app, and you may have spent a lot of time implementing IAP in your app so you can make a bit of money for your efforts (or better still, make a lot of money from your efforts!).  But perhaps like most developers, maybe 2-10% of your customers actually buy anything. It can get frustrating. Now, with Amazon Underground you have the option to monetize your app and get paid based on how much time users actually spend using your app. All your users.

If you are interested in trying out this new monetization model by submitting an existing IAP-based app, the following is a guide for you!

How to Submit Your IAP App to Amazon Underground

At the most basic, you create an Amazon Underground app with copies of your IAP items. These will be marked #ActuallyFree with strikethrough prices so customers can see the value you’re giving them. If you happen to have the IAP amounts hard coded in your catalog UI, you’ll need to change your UI as well.

Before you get started you can read more about Amazon Underground Eligibility and Submission Criteria. Once you’ve gone through the docs, these are the steps you need to preform in order to get your game ready for submission:

Step 1: Make All Your IAP Items Free

Option 1: Re-create and re-submit to the Amazon Appstore using new SKUs for the Amazon Underground version of your app

Set each re-created item to its original IAP price; Amazon will apply strikethrough pricing to your items to show that they are now free. You will also need to update your code base to use the new SKUs. See Submitting Your App and In-App Items for more information on submitting IAP items to the Amazon Appstore.

Note: If you are not already using Amazon's IAP API because your app uses a different in-app purchasing API, such as Google's IAB, you will need to implement Amazon's IAP API to use this option. If your app uses Google's In-App Billing (IAB), see this documentation to learn more.

Option 2: Remove the IAP integration from your app, but provide an alternate mechanism for users to obtain IAP items for free

For example, build a "store" that does not actually make any IAP calls or have any IAP items on the backend but whose items can be purchased through non-monetary ways. Your users could then "buy" items from your store, just as they normally would do for IAP items, but the "currency" for the store could be game experience, time played, or something else. When developing ways to unlock IAP items, keep in mind that you will not be permitted to require users to watch ads to unlock IAP items.

Implementing Option 2 involves the following high-level tasks:

1. Remove the IAP SDK from your code.
2. Modify your purchase execution call to fulfill former IAP items to your users for free:

• Add your own logic for what each former IAP button does, such as a "Buy" button. (This logic is handled by the IAP SDK for non-Amazon Underground apps.)
• Fulfill the item to the customer.

We encourage you to update the icons and strings for your IAP items for Amazon Underground to emphasize to users that they are now receiving these items for free, which will help to communicate to your users the value of the items that they are now receiving for free.

Step 2: Repackage Your App

In order for your game to work with Amazon Underground you will need to create a new APK for your app. This APK will need a unique package name that includes appending the string ".underground" to the original package name for the app. For example, "com.company.example.underground" would be the package name for the Amazon Underground version of "com.company.example."

You can read more about migrating your app on the developer portal.

Step 3: Solution to Migrate User Data

While not required, it would be a good user experience if you ensured that customers of your current app can keep and use any saved data in the new Amazon Underground version as well. There are many ways to do this and we outline a few data migration solutions and best practices.

Step 4: Create New Marketing Material for the Amazon Underground Version of Your App

You will need to upload new screenshots and a new app description to the developer portal. It’s important to explain the value you’re giving customers and call out any additional features of your app as part of the Amazon Underground program. We will automatically add Amazon Underground branding to any assets uploaded through the dev portal so you don’t have to do this manually.

Step 5: Upload Your New App APK

Now you are ready to follow the new submission process for Amazon Appstore through the dev portal. Simply upload your new APK, description and screenshots and submit for approval. Once the app passes testing, your app will be live to all Amazon Underground customers.

More Engagement = More Revenue

The process is fairly simple, and now you will have all the advantages of getting paid for every minute your customers spend in your app while your customers enjoy free engaging items that they may not normally have purchased. The best part of the Amazon Underground program is letting developers focus on making engaging apps and delighting customers while also taking advantage of the fact that each user session will generate money. The longer customers engage with your app, the higher the potential reward. Simply build the app you want to make and that customers want to use and let Amazon Underground help you monetize it automatically.

If you have a game that you think must be re-balanced to work (like a cross platform PvP game, where unlimited game currency would disrupt cross platform play), please let us know about your app. We’d like to work directly with you on this to see how we could support it in the future.

Getting Started is Easy

Sign up for the Amazon Appstore blog to get the latest news: http://bit.ly/AMZNDevBlog

Thanks,

-Mike Hines (@MikeFHines)