A walking simulator is a story-driven game with almost no combat or complex mechanics: you walk through the world, look around, read notes, and listen to the story. The name sounds ironic, but the genre has produced many touching and memorable games. It's like an interactive film or book, where you decide where to look and at what pace.
If you're looking for action, maybe. But if you enjoy storytelling and atmosphere, these games are unforgettable. They're usually short, lasting an evening or two, so they won't take up much time.
Are there any mysteries in them?Sometimes they're simple, to keep the pace up. If you're looking for more challenges, check out the "Puzzle" and "Mystery" tags.
You can download walking simulators via torrent: the filters above will help you choose by language, size, and build type.