TET files exist as 2 different types. Please find information about each of them below.
Type 1: Godot Engine Script Editor Theme
The Godot Integrated Development Environment includes tools developers use to develop, package, and deploy games. The Godot script editor is a text editor developers use to create and edit scripts. TE...
The Godot Integrated Development Environment includes tools developers use to develop, package, and deploy games. The Godot script editor is a text editor developers use to create and edit scripts. TET files contain settings that control how text syntax appears in the script editor. TET files are plain text files that can be opened in any text editor.
The getextension() function to get a file extension no longer exists. With Godot 4.0, check the file type using file.type. GDScript was introduced in Godot Engine 3.1. It can be run in Godot Engine or edited in the script editor. GD files can also edit with text editors, but without the scripting functionality.
To open a TSCN file in Godot Engine, select Open Scene or Open Recent. To create and save a scene as a TSCN file, select New Scene then Save Scene. TSCN files are saved as plain text for easier version control and human reading. Godot Engine typically opens TSCN files, but text editors can also view and modify them.
To enable C# scripting in Godot, set the Mono Editor External Editor to Visual Studio Code in Editor Settings. Then install the C# for Visual Studio Code extension in VS Code.
Godot Engine
Textease Studio CT