Ok, nice and easy then
Your games will either be in tar or zip format.
Upload these to the appropriate directory arcade/tar/ or arcade/zip/ depending on the file extension.
Do not unpack these files.
Once the files have finished uploading go to your admincp > Arcade > Add New Game.
Scroll down this page until you find the list of games that you have just uploaded.
At the end of the list there is a link that says install all games. Click that and wait.
It can take a while depending on the number of games that you have uploaded for installation and your connection speed, so just be patient until it finishes.
Once it has finished, delete the tar or zip files again from your server.
Your games will be installed and ready for use. The only thing that you need to do is sort them into categories if you use them.