We have downloaded the Diablo 3 game client on one PC at our house. With the other two recent Blizzard games WoW and Starcraft 2 you could just copy the game folder from one PC to another over the LAN and fire it up. Is this also possible with the Diablo 3 game client?
I have confirmed this. Just like World of Warcraft, you can move/copy/cut the entire directory (~15GB) to anywhere you would like. I tested this by moving it between hard drives on my local machine.
The only problem would be the shortcuts on the desktop not pointing to the correct location, but you can always use the launcher found in the Diablo 3 container.
Once you have D3 installed on one computer, instead of downloading it again, use an external Hard drive to copy it from computer-to-computer!
While you can copy your Diablo 3 folder to an external hard disk, it is worth noting that Diablo 3 stores additional data in the following locations;
C:\ProgramData\Battle.net C:\ProgramData\Blizzard Entertainment
The 'ProgramData' folder requires administrative privileges in order to write files to this location, so simply 'just' copying your Diablo 3 folder won't work but the Diablo 3 launcher should rebuild these folders and all related files if you have access to these locations.
These folders contain the Battle.Net Agent in addition to Diablo 3 Launcher updates and are required for the Launcher to update.
There is the 'current' copy of the launcher in the Diablo 3 installation folder, so provided you have write access to the above locations on the new computer running this will re-create all of the required folders and re-download all of the required files for the Battle.net agent.