Its a ingame developer console. Like lots of older games used to have.
- Open Unity package manager
- Add package from Git URL
- Paste link
https://github.com/Sacristan/AhhnoldConsole.git
- Import sample command registration (under package description)
- Add imported sample component to any game object
- Press ~ to see the magic!
Uses IMGUI for displaying its content.
Huge inspiration: