On the Xbox Support twitter, Microsoft has stated that they are currently investigating an issues with Xbox Live that include a complete lock down of the ability to launch any games from the system.
The tweet directs people to the Xbox Live status page which, as of writing this, tosses up an error message stating that the status page itself is down.
It is somewhat of an upsetting scenario for people, especially considering that the online check for launching games was supposed to have been completely removed before the system launched. Earlier this year, Brian Shea (who also reported that he has been unable to launch Xbox One games today) argued that Xbox One’s digital game errors are unacceptable and that players should never lose access to single-player games due to server issues.
It is an unfortunate reality of server-based gaming that servers themselves go down occasionally, but how much they take down with them should be minimized as much as possible.
[Source: Xbox Support Twitter]