Xbox Game Preview is an early access program that's coming to Xbox One. It's similar to the system currently in operation over on Steam, albeit with one major difference: console owners will be able to download free trails of games taking part in the program, and thus be able to try before they buy, a feature that certainly takes the risk out of buying unfinished games.
The Long Dark, Sheltered, Elite: Dangerous, and DayZ are the four games that were mentioned during the event. The new program starts up later today so boot up your Xbox One this evening and see the games that are already available.