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SDK Wrapper (Beta)

Keep in mind this project is a Work In Progress, with many features and improvements to come.
 Please leave your feedback.

SDK Wrapper is not endorsed or sponsored by Valve.

SDK Wrapper only supports Windows.

Introduction

As you know from the previous article, there are some essential differences between GOG and other platforms, including Steam. With this tool we aim to decrease the time needed to implement additional features on GOG if you already have a working Steam build (with other platforms planned for future development).
If you already have a Steam version of your product (SDK Wrapper is intended to be used only after you have created your game's Steam build), you can get it up and running on our platform within minutes, not hours. No changes to the code need to be made — all you need is to use our SDK Wrapper (Beta).

Galaxy SDK API is still available alongside SDK Wrapper functionality so it's possible to create custom Galaxy SDK init but leave other functionality like stats or leaderboards to SDK Wrapper.

SDK Wrapper (Beta) is a middle layer that provides interoperability between Steam and GOG Galaxy API calls and speeds up the process of developing GOG builds by translating Steam API calls included in a build already created with Steam in mind into calls that can be understood by the GOG backends.
Not all SDK features are supported yet — and, obviously, some will never be — but basic functionality is preserved. Currently, SDK Wrapper (Beta) allows to use the following features out of the box:

  • achievements,
  • leaderboards,
  • stats,
  • friends,
  • matchmaking (lobbies, lobby data, lobby chat),
  • cloud saves (Remote Storage),
  • DLC detection (via GalaxyConfig.json mapping),
  • game language (ISteamApps::GetCurrentGameLanguage),
  • Steam Input → XInput mapping (partial; see Input actions)

SDK Wrapper is not endorsed or sponsored by Valve.

Offline mode

Games on GOG being DRM-free require that the game is playable even without Galaxy Client installed. Therefore it should be possible to play the game even when SteamAPI_Init returns false, which isn't the case for Steam.
It means that in order to ensure that your game and its online features work, you need to either:

  • keep Galaxy Client running

or

  • allow your game to be able to continue running when SteamAPI_Init returns false (which will result in disabling its online features).

When Galaxy Client is not installed, init_always_true defaults to true automatically so SteamAPI_Init can still return success and the game can run offline (online features remain unavailable until Galaxy is present). Set init_always_true explicitly in GalaxyConfig.json if you need that behavior when Galaxy Client is installed as well.

It's a special case that could imply game's code changes e.g. only replace SteamAPI_Init section with galaxy::api::Init. This feature is still being discussed and worked on.

DLC Discovery and Storage interface's methods using local filesystem (FileWrite/FileRead etc.) are still available even without Galaxy Client running and authorization.

Implementation

  1. Make sure you're using a supported Steam API version.
  2. Add achievements to DevPortal, ideally using the VDF file from Steam.
  3. Download SDK Wrapper (Beta)
    Be advised: download the package that matches the Steamworks version your game was built with. Packages are named GalaxySteamWrapper_<version>_<32|64>bit_Steamworks<steam_version>.tar.gz.
  4. Add SDK Wrapper (Beta) to your game. There are two ways to achieve that. Do one of the following:
    • Option a: Rename GalaxySteamWrapper/Libraries/GalaxySteamWrapper[64].dll to steam_api[64].dll and use it to replace the original steam_api[64].dll file in your already built game.
    • Option b: Recompile your game linking against GalaxySteamWrapper/Libraries/GalaxySteamWrapper[64].lib.
  5. Copy GalaxySteamWrapper/Libraries/Galaxy[64].dll to the same directory as steam_api[64].dll or executable, depending on how working directory and links are handled.
  6. Create a GalaxyConfig.json file where you specify client_id and either client_secret or client_code, and place it in the same directory as steam_api[64].dll (some exceptions may apply; see the Unity section below).
  7. Your build (ideally no rebuild needed if you chose 4.a) is now ready to be uploaded to DevPortal.

Example:

Game folder

![SWGame folder](_assets/steam-wrapper-game-folder.jpg)

GalaxyConfig.json

![SWGame GalaxyConfig.json](_assets/steam-wrapper-galaxy-config.jpg)

Demo game

You can check our SDK Wrapper demo game and its source code for the exact implementation. Ask our support for its license (1931358602 SDK Wrapper Demo Game). Check its source code on GitHub and build it yourself.

Supported Steam API Versions

SDK Wrapper (Beta) can currently support only specific versions of the Steam API headers, and your game must be built with one of them.

Scope Versions
Unit-tested range 1.29 – 1.64
Game-tested 1.29, 1.42, 1.62, 1.64

The authoritative list of downloadable packages is on the SDK Wrapper download page on DevPortal. This documentation may lag behind newly added Steamworks versions.

SDK Wrapper releases are built against Galaxy SDK 1.152.10.

If your game already uses one of the supported versions, no action is necessary. Otherwise, support for other versions of the Steam API headers can be added to SDK Wrapper (Beta), or you may update your current pipeline (your existing build) or set up a new one with a different Steam API version.
Whichever you choose, you can find the list of all Steamworks releases here.

Configuration File

In order for SDK Wrapper (Beta) to know the SDK credentials of your game, they must be specified in GalaxyConfig.json (you can obtain them in Devportal). It is a flat JSON file used for configurations which should be distributed along with the game and located in its working directory — usually where the EXE file is. The only required properties are client_id and either client_secret or client_code. The remaining options are read and parsed during SteamAPI_Init.

client_code

Plaintext client_secret can be used for testing purposes, but it is recommended to use client_code instead when releasing. client_code is an encrypted version of client_secret. You can obtain it by accessing SDK credentials in the games menu.

Minimal Config Example

{
    "client_id": "XXXXXXXXXXXXXXXXX",
    "client_code": "YYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY"
}

Available Options

Option Type Default Description
client_id string required ID of the client
client_secret string "" Secret of the client (required unless client_code is specified)
client_code string "" Code of the client (required unless client_secret is specified)
config_file_path string "." Path to folder containing Galaxy configuration files
storage_path string "" Path to folder for storing internal SDK data
host string "" Local IP address this peer would bind to
port number 0 Local port used for communication with servers and peers
auth_on_init bool true SteamAPI_Init will attempt blocking SignInGalaxy
require_online bool false Indicates if sign in with GOG Galaxy backend is required
auth_timeout int 15 Timeout (seconds) for blocking SignInGalaxy
stats_on_init bool false SteamAPI_Init will call RequestCurrentStats
dlcs array [] DLC mappings between Steam and Galaxy IDs (see DLC mapping)
input_actions array [] Steam Input action-set mappings to XInput (see Input actions)
steam_appid number 100 Steam AppID to use (100 is the default mock ID)
init_always_true bool true¹ Makes SteamAPI_Init return true even when Galaxy init or auth fails
force_callbacks bool false Force callback dispatch on every SteamAPI_RunCallbacks call
force_store_stats bool false Force stats to be stored after every stat write
offline_persona bool false Helps to set the same save/profile path for both online and offline play

¹ Defaults to true when Galaxy Client is not installed; otherwise defaults to false unless set explicitly.

DLC mapping

The dlcs array maps Steam DLC AppIDs to their Galaxy counterparts so that ISteamApps::BIsDlcInstalled, GetDLCCount, and BGetDLCDataByIndex work correctly.

{
    "dlcs": [
        { "steam_id": 1234560, "galaxy_id": 1234567890123456, "name": "My DLC" }
    ]
}
field type description
steam_id number Steam DLC AppId
galaxy_id number Galaxy product ID for the DLC
name string Human-readable name (used in logs)

Input actions

The input_actions array configures Steam Input → XInput button mapping when ISteamInput is active (Steamworks 1.43+). Each entry in the array represents one action set and maps Steam action names to controller button identifiers. You must also ship xinput1_3.dll and goginput.ini beside the main DLL.

{
    "input_actions": [
        {
            "dpad_up": "UP",
            "dpad_down": "DOWN",
            "dpad_left": "LEFT",
            "dpad_right": "RIGHT",
            "button_a": "A",
            "button_b": "B",
            "button_x": "X",
            "button_y": "Y",
            "l1": "L1",
            "r1": "R1",
            "l2": "L2",
            "r2": "R2",
            "back": "SELECT",
            "start": "START",
            "l3": "",
            "r3": "",
            "left_stick": "Move",
            "right_stick": ""
        }
    ]
}

Galaxy Bridge API

In addition to the standard Steamworks ABI, GalaxySteamWrapper.dll exposes a small bridge API (GalaxySteamWrapperApi.h, included in every release package) that gives host applications direct access to the underlying Galaxy SDK without linking Galaxy separately.

Lifecycle

GalaxySteamWrapper_Init(clientID, clientSecret); // initialise Galaxy (alternative to SteamAPI_Init)
GalaxySteamWrapper_ProcessData();                // pump callbacks (call once per frame)
GalaxySteamWrapper_Shutdown();                   // clean up
const char* err = GalaxySteamWrapper_GetErrorMessage(); // retrieve last error string

ID conversion

CSteamID          steamID  = GalaxySteamWrapper_ToSteamID(galaxyID);
galaxy::api::GalaxyID gid  = GalaxySteamWrapper_ToGalaxyID(steamID);

User / auth helpers

bool signedIn = GalaxySteamWrapper_User_SignedIn();
bool online   = GalaxySteamWrapper_User_IsLoggedOn();
GalaxySteamWrapper_User_SignOut();

uint64_t realID = GalaxySteamWrapper_User_GetGalaxyID_GetRealID();
uint64_t id64   = GalaxySteamWrapper_User_GetGalaxyID_ToUint64();

const char* token = GalaxySteamWrapper_User_GetAccessToken();
const char* idTok = GalaxySteamWrapper_User_GetIDToken();

The header also exposes read-only user data accessors, session ID, and encrypted app ticket helpers. See GalaxySteamWrapperApi.h in the release package for the full list.

Bindings to other programming languages

From Steamworks 1.32 onward, the flat API is supported, so projects like Steamworks.NET or Facepunch.Steamworks should work without additional tinkering. The same applies to other projects that call steam_api.dll flat API exports.

CSteamworks is not currently supported.

Manual Callback Dispatch

As of version 1.1.2 of SDK Wrapper, Steam's manual callback dispatch (instead of running all callbacks at once with SteamAPI_RunCallbacks, you can dispatch them manually with SteamAPI_ManualDispatch) is fully supported.
Facepunch.Steamworks moved to using manual dispatch as of 2.3.0, so it should be possible to use this and later versions with SDK Wrapper.

Game engines

Game Engine Notes
Unreal Engine Both native Steam implementation and EOS seem to work, but a little tinkering might be needed.
Unity Appears to work without an issue
Godot Appears to work without an issue
Game Maker Appears to work without an issue
RenPy Some issues regarding working directory/dll placement have been reported

Most issues with bindings and game engines seem to be related to working directory, DLL, or EXE placement. We are working on a better approach regarding these issues.

Unity

Depending on your Steamworks implementation (missing explicit SteamStats()->RequestCurrentStats call in Steamworks.NET, Facepunch) you might need to set stats_on_init flag in GalaxyConfig.json to true to fix achievements not working properly.

Important

Correct placement of the GalaxyConfig.json for Unity games is in the root folder of the game installation directory, next to the game.exe.

Example placement of Wrapper files in the Unity game

.
├── root
│   └── gameTitle_data/
│       └── Plugins/
│           └── x86_64/
│               ├── Galaxy64.dll (new)
│               └── steam_api64.dll (replaced with renamed GalaxySteamWrapper64.dll)
├── GalaxyConfig.json
├── GalaxySteamWrapper.2021.09.28-09.33.33.log (example log file if logging is enabled)
└── game.exe

Godot

If you are using GodotSteam you might need to set stats_on_init flag in GalaxyConfig.json to true.

Unreal Engine

Example placement of Wrapper files in the UE game

.
├── root
│   └── GameTitle/
│       └── Binaries/
│           └── Win64/ (working directory in UE4-built game)
│               ├── GameTitle-Win64-Shipping.exe
│               ├── GalaxyConfig.json (new)
│               └── GalaxySteamWrapper.2021.09.28-09.33.33.log (example log file if logging is enabled)
└── Engine/
    └── Binaries/
        └── ThirdParty/
            └── Steamworks/
                └── Steamv139/ (number may differ if the game uses a different Steamworks version)
                    └── Win64/
                        ├── Galaxy64.dll (new)
                        └── steam_api64.dll (replaced with renamed GalaxySteamWrapper64.dll)
Depending on your Steamworks implementation some changes to Unreal Engine itself might be needed.

Native C++

If your Steam implementation is in native C++, it should work like any other game so the default drag & drop method mentioned above should suffice.

EOS

When using EOS Online Subsystem Steam and blueprints some changes to the engine itself need to be made.
First you need to check which Steamworks version your version of UE supports here: /YourUnrealEnginePath/Engine/Source/ThirdParty/Steamworks/ and Steamworks.build.cs. For UE 4.27 it's Steamv151 so please stick to this version.

Online Subsystem is a private dependency so by default it is statically linked into your project using steam_api[64].dll shipped with the engine thus recompilation is necessary.

This implies drag-and-dropping GalaxySteamWrapper[64].dll and Galaxy[64].dll e.g. here /YourUnrealEnginePath/Engine/Binaries/ThirdParty/Steamworks/Steam[Current Version]/Win64 replacing the original steam_api[64].dll and then recompiling your project.

After recompilation, please make sure to ship your package with GalaxyConfig.json placed in YourPackage/YourProject/Binaries/Win[64] beside your game's executable file and Galaxy[64].dll in YourPackage/Engine/Binaries/ThirdParty/Steamworks/Steam[Current Version].

Writing achievements fails (UE4)

Check exactly how achievements are defined in the OSS configuration file in the engine. In case of Nemezis: Mysterious Journey III, achievements were declared in polish-style quotes (“NMJ_FIRST_PUZZLE” instead of "NMJ_FIRST_PUZZLE"). Steamworks offers some support against this; Steam Wrapper does not.

Example placement of Wrapper files in the Misc engine

.
├── root
├── Galaxy64.dll (new)
├── GalaxyConfig.json (new)
├── GalaxySteamWrapper.2021.09.28-09.33.33.log (example log file if logging is enabled)
├── Game.exe
└── steam_api.dll (replaced with renamed GalaxySteamWrapper.dll)

Methods Implemented

Note: Unlisted methods are not implemented (or return safe stub values).

SteamClient Interface

Method Supported Remarks
SetWarningMessageHook Yes Does the same as SteamUtils::SetWarningMessageHook: outputs GOG Galaxy error messages

SteamApps Interface

Method Supported Remarks
BIsSubscribed Yes Always returns true
GetCurrentGameLanguage Yes Mapped from Galaxy language codes
GetAvailableGameLanguages Simplified Returns current language only
BIsSubscribedApp Yes Always returns true
BIsDlcInstalled Yes Requires DLC entry in GalaxyConfig.json
GetDLCCount Yes Based on dlcs config entries
BGetDLCDataByIndex Yes Based on dlcs config entries
Other ISteamApps methods No Return stub values

SteamMatchmaking Interface

Method Supported Remarks
RequestLobbyList Yes Does not auto-request data for each lobby; call RequestLobbyData per lobby if needed
AddRequestLobbyListStringFilter Yes
AddRequestLobbyListNumericalFilter Yes
AddRequestLobbyListNearValueFilter Yes
AddRequestLobbyListFilterSlotsAvailable No
AddRequestLobbyListDistanceFilter No
AddRequestLobbyListResultCountFilter No
AddRequestLobbyListCompatibleMembersFilter No
GetLobbyByIndex Yes
CreateLobby Yes
JoinLobby Yes
LeaveLobby Yes
InviteUserToLobby Yes Uses Galaxy friend invitations
GetNumLobbyMembers Yes
GetLobbyMemberByIndex Yes
GetLobbyData Yes
SetLobbyData Yes
GetLobbyDataCount Yes
GetLobbyDataByIndex Yes
DeleteLobbyData Yes
GetLobbyMemberData Yes
SetLobbyMemberData Yes
SendLobbyChatMsg Yes
GetLobbyChatEntry Yes
RequestLobbyData Yes
SetLobbyGameServer No Logged only
GetLobbyGameServer No
SetLobbyMemberLimit Yes
GetLobbyMemberLimit Yes
SetLobbyType Yes
SetLobbyJoinable Yes
GetLobbyOwner Yes
SetLobbyOwner Yes
SetLinkedLobby Yes
Favorite games / server list APIs No
ISteamMatchmakingServers No
ISteamParties / ISteamGameSearch No

SteamRemoteStorage Interface

Method Supported Remarks
FileExists Yes
FileRead Yes
FileWrite Partially No checking for reaching file limits or invalid paths/filenames
GetFileCount Yes
GetFileSize Yes
GetQuota No

SteamUser Interface

Method Supported Remarks
BLoggedOn Yes
RequestEncryptedAppTicket Yes

SteamUserStats Interface

Method Supported Remarks
RequestCurrentStats Yes
GetStat (integer) Yes
GetStat (float) Yes
SetStat (integer) Yes
SetStat (float) Yes
UpdateAvgRateStat Yes
GetAchievement Yes
SetAchievement Yes
ClearAchievements Yes
GetAchievementAndUnlockTime Yes
StoreStats Yes
GetAchievementDisplayAttribute Yes
FindOrCreateLeaderboard Yes
FindLeaderboard Yes
GetLeaderboardName Yes
GetLeaderboardEntryCount Yes
GetLeaderboardSortMethod Yes
GetLeaderboardDisplayType Yes
DownloadLeaderboardEntries Yes Cannot be called with k_ELeaderboardDataRequestUsers, as in Steam
DownloadLeaderboardEntriesForUsers Yes
GetDownloadedLeaderboardEntry Yes
UploadLeaderboardScore Yes

SteamUtils Interface

Method Supported Remarks
SetWarningMessageHook Yes Does the same as SteamClient::SetWarningMessageHook: outputs GOG Galaxy error messages
GetAppID Yes Uses steam_appid from config when set

SteamFriends Interface

Method Supported Remarks
GetClanActivityCounts No Always sets arguments to 0
GetFriendsGroupName Simplified Assumes everybody is in a single group, always returns Friends.
GetFriendPersonaNameHistory Simplified Assumes no history exists
GetPlayerNickname Simplified Assumes no nickname is set
GetFriendsGroupCount Simplified Groups are not supported; assumes everybody is in a single group
GetFriendCount Partially In the friend flags passed to this method, only k_EFriendFlagImmediate is supported
GetFriendByIndex Partially In the friend flags passed to this method, only k_EFriendFlagImmediate is supported
HasFriend Partially In the friend flags passed to this method, only k_EFriendFlagImmediate is supported
SetRichPresence Partially No custom keys; only status, metadata and connect allowed
GetFriendRichPresence Partially No custom keys; only status, metadata and connect allowed
GetFriendSteamLevel No Returns 0
GetClanCount Simplified Returns 0
GetFriendsGroupMembersCount Partially Returns friend count regardless of a group
GetFriendsGroupMembersList Partially Returns friend list regardless of a group
GetFriendRelationship Partially Returns only k_EFriendRelationshipFriend or k_EFriendRelationshipNone
GetPersonaState Partially Returns only k_EPersonaStateOnline or k_EPersonaStateOffline
GetFriendPersonaState Partially Returns only k_EPersonaStateOnline or k_EPersonaStateOffline
GetUserRestrictions Partially Returns only k_nUserRestrictionNone or k_nUserRestrictionUnknown
GetPersonaName Yes
SetPersonaName No
GetFriendPersonaName Yes
GetFriendGamePlayed No
GetFriendsGroupIDByIndex No
GetClanByIndex No
GetClanName No
GetClanTag No
DownloadClanActivityCounts No
SetInGameVoiceSpeaking No
SetPlayedWith No
GetSmallFriendAvatar Yes
GetMediumFriendAvatar Yes
GetLargeFriendAvatar Yes
RequestUserInformation Yes
RequestClanOfficerList No
GetClanOwner No
GetClanOfficerCount No
GetClanOfficerByIndex No
ClearRichPresence Yes
GetFriendRichPresenceKeyCount Yes
GetFriendRichPresenceKeyByIndex Yes
RequestFriendRichPresence Yes
GetCoplayFriendCount No
GetCoplayFriend No
GetFriendCoplayTime No
GetFriendCoplayGame No
GetFollowerCount No
IsFollowing No
EnumerateFollowingList No
IsClanPublic No
IsClanOfficialGameGroup No

Flat API

From Steamworks 1.32 onward, flat API functions shipped with Steamworks are supported with some exceptions. The following flat exports are stubs (they log and return empty/default values) because they depend on Steam-private behavior or unsupported platforms:

Method
DestructISteamHTMLSurface
RequestPublisherOwnedAppData (Steam ≤ 1.36)
GetPublisherOwnedAppData (Steam ≤ 1.36)
Set_SteamAPI_CPostAPIResultInProcess (Steam ≤ 1.36)
Remove_SteamAPI_CPostAPIResultInProcess (Steam ≤ 1.36)
RunFrame
Set_SteamAPI_CCheckCallbackRegisteredInProcess
SetXboxPairwiseID
GetXboxPairwiseID
SetPSNID
GetPSNID
SetStadiaID
GetStadiaID
ShowModalGamepadTextInput
GetConfigValueInfo (Steam 1.52)
IterateGenericEditableConfigValues (Steam 1.52)
ResetIdentity (Steam 1.52)
SetIPv4Addr (Steam 1.53)
GetFakeIPType (Steam 1.53)
GetIPv4 (Steam 1.53)
IsFakeIP (Steam 1.53)

Also SteamTV and SteamVR flat interfaces are not supported.

Keep in mind this project is a Work In Progress, with many features and improvements to come.
Please leave your feedback.

SDK Wrapper is not endorsed or sponsored by Valve.

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