How to stop the infinite reboot loop
When you run Anno 2070 Complete (and sometimes other editions) for the first time, after the opening credits it will inform you that an add-on activated and the program needs to "reboot". For a lot of people what happens next is that a command prompt window opens with some telemetry on your system files, and then the previous instance of the programs either crashes or exits and a new instance of the program opens. This new instance then says that the program needs to reboot again. This cycle then continues infinitely (https://www.youtube.com/watch?v=bWu3Uskn7GM).
All this is due to changes Ubisoft made related to the autopatcher 2 years ago and still hasn't fixed (https://www.reddit.com/r/anno2070/comments/2osj3g/uplay_updates_breaking_anno/). This can be worked around by replacing AutoPatcher.exe with one of two versions. In either version it may ask for a key, as the deep ocean expansion has Tages SolidShield DRM, and you simply enter your uPlay key for Anno 2070 again. You can do this either by running the game and letting it reboot to run AutoPatcher.exe or in some cases running AutoPatcher.exe first directly. Don't worry if you get a warning about a missing manual or the game itself crashes when launching the autopatcher.
The first AutoPatcher.exe replacement is relatively small (3MB download, 10MB expanded) and downloads the required files. It is available at: http://www.mediafire.com/download/nadctxtyn69cneg/AutoPatcher.rar. It is relatively ideal due to its size but this is the "unofficial" workaround.
The other AutoPatcher.exe replacement, and official workaround, is to download a massive 1GB offline version of AutoPatcher.exe from: http://static2.cdn.ubi.com/patches/anno2070/Anno2070_Offlinepatcher_2_00.zip. After all the extracting is done the game stops asking to reboot, generally you should be able to replace massive offline version with the default AutoPatcher.exe from the initial install.