Topic on Talk:The big list of third-party DRM on Steam
Denuvo Anti-Tamper appears to use online authentication of a hardware hash (hence the existence of an offline activation page for Lords of the Fallen) which sounds like standard DRM behaviour to me.
I don't have a Denuvo game to test this for myself but it seems like it wouldn't be possible to install and play one of these games if the server isn't available for this first-run authentication process.
Their assertion that it assists existing DRM is because it authenticates the hardware hash against a Steam/Origin account rather than a traditional product key (so it isn't a standalone solution).