Forza Motorsport 5 will be available on launch day for Xbox One, but will also require a day one patch to play.
Turn 10 Studios’ Dan Greenawalt was speaking to IGN on the matter, saying that the download will enable players to use the Drivatar system that was being touted back at E3. The reasoning behind the delay is due to the studio attempting to finish Forza 5 in time for Xbone’s launch in November:
“So when you first boot up the game, we’re going to ask you to log in. And when you log in you’re going to get the Drivatars and you’re also going to get a whole bunch of content: tracks and cars. Our production schedule is such that we are putting them in as late as possible and that means making them free as downloadable content on Day One. [But] that is required content to play the game. We basically have designed the game to work with all that content no matter how late [it’s] coming in, in order to make the biggest game possible.”
Even though this update is indeed required in order to play the game, like Microsoft’s reversal stated, you will be able to play the game offline.