NON-DENUVO GAMES Open up Steam and use 'Change user'. Before you log back in to your own account, open up the Network and Sharing Center. Be ready to disable your ethernet or wifi adapter quickly. Log into Steam, and immediately right-click and disable your ethernet/wifi. With the right timing, the games will show as playable, even if the library is in use. DENUVO GAMES I've noticed that Denuvo titles will occasionally disallow you from playing them after having been offline for a while, instead producing the message that "for first launch, you must start the game online, log in and reset Steam" etc. etc. In order to circumvent that - first follow the steps above, and then... 'Play' the Denuvo-protected game. A Steam window should appear instantly telling you that the game is launching. This will take a few seconds. After that, normally, the game will inform you that you need to launch it online to play it. However, if you re-enable your internet for a single second, and then disable it again, Denuvo will have time to 'phone home' before Steam has a chance to kill the game process. At that point, you're ready to play - for extra reliability, you can exit Steam and log back in following the above non-Denuvo steps, because you can now boot the Denuvo game for between several hours up to several days before it forces you to start the game online again.