Game Launcher Documentation

By CodeSpartan

Game Launcher Documentation

Initial Setup

Uploading a new game build

Common issues


What about Steam Launcher?

Initial Setup

The following steps need to be done just once:

1. Go to uploader/ folder, open Settings.ini and fill in the values, for example:


GameDirectory=D:\MyGame\WindowsNoEditor                your packaged game folder (no trailing slash)

TempFolder=I:\temp                                        a folder to store temp files (no trailing slash)




FtpPath=/public_html/launcher/                                a web folder on your ftp

NOTE: While the launcher is cross-platform (Mono), the uploader currently needs a Windows machine.

2. Upload the contents of the deployer/ folder to the FTP folder that you input as FtpPath in the previous step.

3. In your browser, go to the FtpPath folder and login with these credentials:

User: admin

Password: 123456


4. Click “Change Password” and change your password.

5. Open launcher/LauncherSettings.ini and fill in the http path (the same folder as in p.3) and the path to your game’s exe, for example:




6. All done! Now you can distribute the launcher to your users and upload the game build (see next section)

Uploading a new game build

The following steps are the same whether you upload a build for the first time or not:


  1. Run uploader/GameUploader.exe and wait until it has finished uploading:


  1. Log in to the control panel and click Deploy new version:


  1. Done! Now when the user runs the launcher, it will download the changed files.

Common issues

Error: 553 filename not allowed

Solution: double-check your FtpPath in Settings.ini. It should be the same as after you connect with Filezilla/FlashFXP/other FTP client. If the correct folder opens right after connecting with Filezilla/FlashFXP, then you can just put “/” in FtpPath.

Error: When I hit “Play” in the launcher, I get “Unhandled exception”

Solution: Check the ExePath in LauncherSettings.ini. The path should start with Game/  and lead to your game’s .exe file.

Error: Launcher error "Value was either too large or too small for an Int32"

Solution: Unchecking “Use Pak Files” in packaging settings in UE4 should fix this. PAK files don’t protect anything since they can be unpacked using the .exe that comes with UE4 and they don’t work well with incremental updates, so I don’t use them.

Error: Launcher error “One or more errors occured”

 This error is most likely thrown because there’s no hash.xml in the root of deployer folder. Make sure you’ve deployed the game and that it created hash.xml and emptied the “newupdate” folder. If it didn’t do that, try adjusting the folder permissions.

Error: Fatal error: Class 'ZipArchive' not found

Solution: you have to enable “zip” php extension. With some hosting providers, such as GoDaddy, you can do it from cPanel:



Art by etcgood ( )

Click sound by LittleRobotSoundFactory

What about Steam Launcher?

If your game is Greenlit, or approaching Greenlight, you usually have 3 choices:

  1. Use double launchers - your own inside the Steam one. This is redundant and most users won’t like it. Not recommended.
  2. Manage two depots, one for Steam users and one for non-Steam users. This is better user experience but you will have to upload each build to both depots, and this will take large amounts of time. Not recommended.
  3. (recommended) Use a single launcher (Steam) after Greenlight to save you time and provide the best user experience. The game doesn't have to be in Early Access or released yet, it can be in closed testing/backers’ testing stage while already using Steam launcher to distribute. Your game will have to be Steam-exclusive, at least for a while. I recommend this approach and that’s what we’re doing with Project Genom.

So if you plan to be on Steam soon and don’t mind being Steam-exclusive for a while, it’s best to treat MMO Kit launcher as a temporarily launcher and don’t spend too much work on it.