Multi-Platform Project

Developing a multi-platform game project comes with unique challenges and trade-offs. This article explores common questions and practical solutions for fresh game developers. While no single code base can cover every platform, careful planning and smart engineering can make multi-platform development much more manageable.

Introduction

It’s a common myth that one code base will run seamlessly on all platforms. In practice, multi-platform projects rely heavily on conditional compilation—using script defines, build targets, and sometimes separate branches—to handle platform-specific requirements. This article explains these challenges and introduces several approaches to streamline your workflow.

Considerations

Platform vs. Build Target

• Platform: Refers to distribution channels (e.g., Steam, Epic Store, Game Pass) as well as hardware (e.g., Xbox, PlayStation, Switch). A platform often has its own API or service requirements.

• Build Target: The actual operating system or device environment (e.g., Windows, Mac, Linux, Android). A single build target might support multiple platforms, but each can demand specific code.

Using conditional compilation in the editor can lead to missing objects or broken references. For example, disabling a Steam API block for testing can cause Unity to strip out important configuration data when the scene is saved.

Unit Testing Challenges

Testing in a multi-platform project is tricky:

• Editor vs. Build: The code in the editor (most inclusive) can differ substantially from the stripped-down version produced for a specific build target.

• Platform-Specific Code: Switching the editor build target may remove necessary scripts, causing test failures or reference losses.

Solutions

Parallel Development

A rigorous ALM/DevOps setup allows you to maintain parallel branches for each platform. This approach lets you integrate common code changes easily, but it requires strong engineering discipline and robust tooling.

Build Service

For smaller projects or those with limited platform-specific code, a build service can manage platform-specific compilation. Typically, you keep your editor set to a common target (e.g., Windows or Mac) and use the build service to generate versions for each platform. This minimizes the risk of the editor stripping out necessary code.

Multi-Project Approach

Though error-prone and labor-intensive, maintaining separate Unity projects (or similar structures in other engines) for each platform can be a solution when advanced tooling isn’t available. This “poor man’s parallel development” requires manually syncing common code, but tools like asset export/import can help streamline the process.

Engine-Specific Examples

Unity Example

Unity projects often face challenges with conditional compilation. Consider the following approach that uses editor-specific code and script defines:

// This code is always included in the Unity Editor
#if UNITY_EDITOR
#define STEAM_PLATFORM
//#define EPIC_PLATFORM
#endif

public class PlatformManager : MonoBehaviour
{
    void Start()
    {
#if STEAM_PLATFORM || UNITY_EDITOR
        // Steam-specific initialization
        Debug.Log("Initializing for Steam.");
#endif

#if EPIC_PLATFORM
        // Epic-specific initialization
        Debug.Log("Initializing for Epic Store.");
#endif
    }
}

This snippet shows how to enable platform-specific code during development while keeping the editor configuration intact.

Unreal Example

In Unreal Engine, preprocessor directives and macros are used to manage multi-platform code. For instance, you might use platform-specific sections in your C++ code:

#include "PlatformManager.h"
#include "Engine/Engine.h"

void UPlatformManager::InitializePlatform()
{
#if PLATFORM_WINDOWS
    UE_LOG(LogTemp, Log, TEXT("Initializing for Windows."));
#elif PLATFORM_XBOXONE
    UE_LOG(LogTemp, Log, TEXT("Initializing for Xbox One."));
#else
    UE_LOG(LogTemp, Log, TEXT("Initializing for default platform."));
#endif
}

Using Unreal’s built-in platform macros (such as PLATFORM_WINDOWS or PLATFORM_XBOXONE) ensures that the appropriate code is compiled for each target.

Godot Example

Godot handles multi-platform development by allowing you to query the platform at runtime and use conditional logic. For example:

func _ready():
    var platform = OS.get_name()
    if platform == "Windows":
        print("Initializing for Windows.")
    elif platform == "X11":
        print("Initializing for Linux.")
    elif platform == "OSX":
        print("Initializing for macOS.")
    else:
        print("Initializing for default platform.")

This GDScript example demonstrates a runtime check to adjust behavior based on the detected platform. Although not compile-time, it helps keep platform-specific logic organized.

Conclusion

There is no one-size-fits-all solution for multi-platform development. Whether you choose parallel development, a build service, or a multi-project approach, each method has its own trade-offs. By understanding the distinctions between platform and build target and leveraging engine-specific tools, you can better manage your project’s code base. This guidance should help you make informed decisions and streamline development across Unity, Unreal, Godot, and beyond.