Hero Mode In Zelda: A Link Between Worlds
Eiji Aonuma has stated that players can unlock Hero Mode in The Legend of Zelda: A Link Between Worlds after completing their first playthrough. He also stated that the game was developed with a team of only 90 people and the creative process began shortly after the release of The Legend of Zelda: Spirit Tracks. The Hero Mode is the same as it is in Wind Waker HD and Skyward Sword; enemies deal double damage and hearts are not found in the grass.
The ability for Link to transform into a wall painting to traverse into previously inaccessible places was inspired by the battle with Ganondorf in The Legend of Zelda: Ocarina of Time with “Phantom Ganon” where he goes into the paintings. Aonuma also made mention of possibly having a Dark Souls inspired Zelda spin-off game.
(Sources: Nintendo Everything, Games Welt)