Roger Zelazny is not mentioned as often as he should be when the topic of sci-fi/fantasy greats comes up. And yet he won six Hugos and three Nebulas, and his Chronicles of Amber, particularly the first five books (the Corwin saga of the 1970s) are rightly considered classics of the genre. Zelazny liked to play with themes of immortality and power, and his Amber opus is no different. The princes (and princesses) of Amber are long-lived demigods who wander the worlds of shadow between the two "true" worlds of Amber and of Chaos, using that shadow to create realities that suit their whims. The Earth we recognize is just one of these myriad shadow worlds, and while the narrative begins there, it rapidly spins away into various fantastical settings.
At heart, the Chronicles of Amber are a tale of war and family politics, as the children of Oberon, the missing King of Amber, vie to replace their father as monarch. The shadow-bending powers of the siblings pale next to their Machiavellian machinations as alliances flow and ebb between protagonist Corwin, vain Eric, unpredictable Random, fiery Bleys, mystic Brand, and their brothers and sisters. One of Zelazny's wonderful invented conceits is the deck of trump-style cards each child of Amber carries, with a family member's image on each card. The immortal royals use these to communicate with each other and even travel, a sort of iPhone teleporter. It's a neat device.