Landstalker: Treasure of King Nole is an action-adventure (+part RPG) with a Japanese flavor, created by Climax Entertainment for the Sega Genesis/Mega Drive and released in 1992.
Designed and directed by Kenji Orimo, Landstalker is very difficult to classify. It's set mostly inside dungeons, where our hero will have to defeat plenty of monsters. But it's not a "hack & slash" RPG. There are also towns and non-players characters to interact with, but the role-playing elements are very light. The story of Nigel and the nymph Friday, searching for the Treasure of King Nole, is complex, and the characters are very well-defined. They are funny and intelligent, and you will fall in love with them. The character design is almost at the level of famous adventures such as The Secret of Monkey Island.
Then you can add the platforming elements: Nigel can jump, climb ropes, and solve puzzles by interacting with objects. At some points, you will think it's a platformer. In other words, it's a lovely mix.
You will be tempted to compare this to Zelda, but the games are different. Zelda is more action-oriented.
But what matters is that Landstalker is a fantastic game. If you start playing it, you will discover an enjoyable experience and get addicted very soon. There is a reason why Landstalker was the main reason to buy the Mega Drive in Japan. Try it and see it for yourself!