Wesnoth is the magical kingdom that forms the background for the turn based strategy\role playing game Battle for Wesnoth. Part of the design philosophy of the game's designers was to keep things simple, and it seems they have chosen this same philosophy when designing the plot of the game.
The land of Wesnoth is unabashedly fantasy, with a society and culture straight out of the Tolkien\TSR tradition. The game doesn't try to avoid fantasy cliches, and is full of wise, white bearded old wizards, brave young warriors, evil queens, standoffish elves equipped with bows, gruff dwarves living in caverns, hordes of marauding orcs, and trolls with one syllable names. This doesn't detract from the plot of the game, since the game's campaign designers manage to make the old cliches interesting enough to carry the game along.
Wesnoth itself is a name of a kingdom on what seems to be the main continent of a larger world. The kingdom itself is a wide, flat river plain with warm, temperate weather. It is populated by humans, and is ruled by a feudal hierarchy. It's capital is the fortress of Weldyn. On the fringes of Wesnoth live human beings who are either outlaws, or are just not strongly affiliated with the Kings of Wesnoth. To the North of Wesnoth, across the Great River, live the orcs and goblins, who periodically go to war with the humans. To the South, and also to the Northeast, live groups of Elves, a race that is generally allied with the humans, but prefers to stick to their sylvan lands. Far to the North is the city of Knalga, home of the dwarves.
From this basic stock of plot elements, the game designers have managed to draw a variety of plots, based around the interactions between these races. Some of the stories advance the history of Wesnoth, while others use it for a generic background for hacking and slashing.
The chief developer of the game actually came up with the name "Wesnoth" as a collection of good sounding syllables. After the fact, a campaign was written describing the name as a result of Wesnoth originally being settled by human refugees coming from an isle to the "West-North".