This mechanic is where players are able to explore open worlds or new locations. This constantly adds gameplay to the game and keeps players playing. This mechanic also applies to items within a game.
A good example of this is in the game Rust. The players are online in an open world. To craft new items the players must first explore and discover blueprints that allow them to have the option to create these new items. These new items can be anything ranging from weapons to building structures. This mechanic keeps players playing as it forces them to explore out in the land and discover places which they can then set up their base with the blueprints that they have found.
Another game that uses this mechanic is Civilization V. This is a strategy game where players have work through the eras to acquire the best possible weapons. They then battle with the other players to conquer the world. There are many ways in which this game uses this mechanic but there are two examples that are fundamental to the play of the game. The first is that when the player spawns the world is covered by fog making the player unable to see the special places in the land. The player must explore to remove the fog and discover these beneficial places. Another way it uses the mechanic is that players must learn skills by playing turns and discovering the abilities.