Myst was a pretty good game that pioneered non-verbal storytelling in video games, as well as pre-rendered graphics. While Myst is was ahead of it's time (and still enjoyable today), it does show its age. Everything that Myst did well in 1992, Riven does 10 times better.
Riven was made in 1997, I played it in 2016 and I can't believe how good the game looks. It's a huge leap from Myst, and probably the best-looking game I've ever seen. Every detail, from the natural world, to the flora and fauna, to the native villages, looks amazing. I can't think of any other game that manages so well to immerse you in a completely alien, but believable environment.
This immersion lends itself very well to the puzzle and exploration-based gameplay. Instead of looking for keys, or solving math-based puzzles, Riven's puzzles are based on observation of the world around you. While walking through the village, you pick up on small details which teach you about their culture. For example, the villagers carve statues in the temple of a whale-like creature, with offerings of food in front of it - meaning they revere the whale as a holy creature.
The gameplay itself is nothing out of the ordinary compared to Myst. There is a LOT of backtracking in the game, but both the graphics, and the subtle cultural clues make it so that exploring almost never gets boring. I must have walked through some areas at least a dozen times, but each time I did, I noticed things that I didn't realize before. Why are the trees stripped of bark? Where do all these pipes lead? Why is the number 5 so prominent in all the architecture?
In addition to learning about the culture of the Rivenese people, the environment also gave a lot of insight into the prominent characters: Atrus, your benefactor from the first game; Catherine, his wife; and Gehn, his villainous father. Given how shallow the characters were in Myst, I really didn't expect much out of the cast. The more you explore the islands, the more you learn about Gehn in particular; his role in the Rivenese society, and the reasoning bahind all that he does. By the time you meet him, you already know some of his story, and you have an idea of what to expect. Also the acting is a big step up from the first game.
Obviously Myst and Riven are not for everyone, but if you have the patience for a slow-paced game, Riven is very rewarding. If you like the atmosphere of games like Metroid Prime, or Shadow of The Colossus, you'll definitely appreciate all the effort that went into making Riven.
If you liked Myst, you must play Riven. If you didn't like Myst, Riven is much better in every way, and you should still try it. It's a game that really makes a lasting impression. Great ending, too.