Install
Run the installer. No admin rights needed. It adds a Start Menu shortcut and opens the launcher.
One installer. Automatic updates.
Download Helbreath Abaddon.
One small installer sets up the launcher. The launcher downloads the game, keeps it up to date and connects you to the realm.
Windows may warn you. Because the installer is new, Windows can show "Windows protected your PC". Click More info, then Run anyway.
Update
The first launch downloads the game. After each patch, only what changed is downloaded.
Play
Press Play, create your account on the login screen and pick your nation.