SLIDGE has a whole bunch of parts to it, but it can be simplified into just 2 story-telling ideas and 3 major types of visual content.
The storytelling ideas are Scenes and Moments.
Moment : Any arrangement of text and other content on the screen. Moments are played in order, and can be used to create sequential dialog between several characters, or a short animated sequence.
Scene : A set of moments. A scene may link to any other scene, so you can assemble parts of your game's dialog as you need.
The major types of visual content that may be displayed during a moment are textbox, choice, and character
Textbox : Text may be entered into one or several textboxes, and each can be set to reveal text like a typewriter or all at once. Textboxes can have a visual style assigned to them to customize appearance.
Choice : Similar to textbox, but choices can link to other scenes or can compute and modify game data.
Character : Portraits of characters (or other images) may be displayed. Characters may have multiple “expressions” defined, allowing you to choose between a character's appearances as you edit.
Continue to First Steps to learn how to use this engine with GameMaker Studio 2.
For further explanation of the terms, check out glossary_of_terms