For more information, check out the FAQ

Players can also install games directly through the app and, if you choose to leave the app running on your desktop,

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 keep them up-to-date automatically even while you’re away from your computer. Please note that it’s entirely up to you whether you wish to leave the app running—you can exit it at any time,

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and it will automatically re-launch whenever your standard launchers would.

For more information, check out the FAQ.