Tip: If you have never used the Unity Editor before, start with the First time users documentation.
Everything in the Unity documentation, other than the 2D section, is relevant to 3D game development.
The first two choices you must make are your 3D render pipelineA series of operations that take the contents of a Scene, and displays them on a screen. Unity lets you choose from pre-built render pipelines, or write your own. More info
See in Glossary and the platforms you want to support. These choices affect each other: some platforms don’t support the High Definition Render Pipeline (HDRP).
To get started, review the documentation for:
If you need to import assets from third-party applications, check that all applications can produce formats that Unity can import. For more information, refer to Supported asset type reference.
What you focus on next depends on your role, but if you’re a sole creator, you might want to consider the following: