In a series of tweets, Spencer answered a range of fan questions about the new feature, which is currently in testing for Preview members and is scheduled to roll out for everyone this fall.
Among other things, he talks about bringing Microsoft's entire lineup of first-party Xbox 360 games to Xbox One via backward compatibility, and also spells out some of the challenges, including licensing and save games.
Check out some of the questions and answers below. Note that Spencer refers to backward compatibility as BC.
@CameronMines Some games, racing is most difficult, can have licensing issues (songs, logos etc.) but we want to support BC completely.— Phil Spencer (@XboxP3) July 10, 2015
@Jimk183 We'll announce more games later but 1st party will be a big participant in BC so great assumption that it will be supported.— Phil Spencer (@XboxP3) July 10, 2015
@Mikey1601 Preview as really us working on emulation, not the portfolio, with the way BC works it's more about getting emulation right.— Phil Spencer (@XboxP3) July 10, 2015