According to the Blizzard, the world of Sanctuary is about to get a whole lot bigger. Diablo III Reaper of Souls’ Adventure Mode will have all way-points unlocked and players can freely explore and play the game across all Acts. The mode can be accessed at any time along with various difficulty levels. You can switch between modes at any time. Adventure Mode is packed with two new game play features the Bounties and the Nephalem Rifts. Bounties provide with guided experience withing a specific Act an are optional, randomized objectives. Bounty hunters receive item Rift Keystones, which gives you access to Nephalem Rifts (ex Loot Runs). Nephalem Rifts are dungeons that are completely randomized and feature random interior and exterior, layouts, lighting and weather, monsters etc.
Via: battlenet