According to the answers to frequently asked questions regarding the game Suicide Squad, it will always require an Internet connection, even if you are playing a single game:

“Yes, an internet connection is required to play Suicide Squad: Kill the Justice League solo or via online co-op”.

The exact reasons for the need to constantly connect to the Network are not known, but there are rumors that this is somehow related to the cooperative game mode. This also means that if the game’s servers are shut down by the developers in the future, players will no longer be able to play the game even on physical media.

Most game developers use a one-time DRM verification system, which is much more convenient, since an Internet connection is only needed once, and then users can play games offline.

Source: videogameschronicle