A recent trend in video games these past few years is the requirement of internet connection to play. As of late however, publishing companies have began to introduce this restriction even to single player games. Diablo 3 for example was criticized for requiring to have a stable internet connection to play, when none of the entries to the series preceding it required this.
This is mostly due to DRM (Digital Rights Management) and to ensure that no cheating or hacking takes place. A publisher known to implement these rules into some of their games is Electronic Arts. This is exactly what transpired when Electronic Arts released SimCity 2013. The game received backlash for being plagued with connection issues, and requiring a stable and constant internet connection in order to play it.
It seems as though Electronic Arts has learned from this experience, as they not only apologized for releasing SimCity 2013 in that state, they also dialed back this restriction in future games. Unlike other games under EA, you can play The Sims 4 offline with relative ease. Keeping up with the standard set by previous entries in the franchise.
To run The Sims 4 offline, all you have to do is open Origin as you normally would. There will be an option to open Origin without connecting to the internet, select that. From there, just navigate over to your games library and run The Sims 4 offline.
Please keep in mind that although an internet connection is not required to play, it does enhance your game. Being online gives you access to the Gallery, a place where you can upload your own creations from within the game, and download the works of others. Playing The Sims 4 offline also disables the ability to share any photographs you take in game to Twitter or Facebook.