When adding code to a project, class names cannot be used if they contain a portion of the project's names and the type of class of the parent. Message says that the name is already used by another class.
If a project is named "forest" then "forestGameMode" is auto-generated. However when using Add Code to Project to create a custom game mode, names such as "restGameMode" or "tGameMode" cannot be created.
1. Open UE4 Editor
2. Create new project with unique name (Unreal)
3. Add code to project based on Game Mode
3. Name the class "realGameMode".
Head over to the existing Questions & Answers thread and let us know what's up.