I didn't meant to copy the Launcher of any of that 1:1, only make something similar with the ability to:
-get a notification if a new version is available along with the release notes that you can read
-decide to either upgrade the current version to new or install it separately also be able to select which version you want to install
-be able to choose which version you want to launch
-manage projects which project uses which version
-manage DLC's, which DLC you want to be installed and get updates through the launcher
-install and manage templates if TGC ever decide to offer anything like that
The whole version thing may be not necessary if TGC be able to maintain backward compatibility but in case need to break compatibility, it can be useful to be able to install and manage multiple versions of AGKS and able to manage which projects uses which version...