For me, Riven was a game changer. It's immense and beautiful world. It's gorgeous soundtrack and it's enticing puzzles became for me the standard for adventure games, and few if any titles have ever matched the feeling I got discovering the world of Riven.
Riven, like Myst once again puts you in the role of an unnamed protagonist. This time you're sent by Atrus into the collapsing world of Riven to stop his psychotic father, Gehn and rescue his wife Catherine. Riven drops you right into the action and gives you nothing to go on other than a short journal by Atrus describing his attempts to save the world and his wife. Everything else you learn by exploring the rich world, moving through structures that depict Gehn as a God, villages, palaces and secrets. Despite the lack of hand holding, Riven, like Myst is easy to pick up and play thanks to its simple interface.
Like Myst, the world you interact with is largely deserted of people, save for a few cutscenes. So if you need to have heart pounding action in your game, or heavy dialogue, Riven will disappoint you. The thrill of Riven is more subtle. It comes from a feeling of being part explorer, part archeologist picking through the relics of a world beautifully imagined and brought to life.