Dark Souls

You play a cursed undead in a dying kingdom, set the task of either ending the age or prolonging it. The game is famous for being hard, but the more interesting thing is how it is built. The whole world is one connected place, with shortcuts that loop back and surprise you, so the map slowly becomes something you know by heart. There are no difficulty options and very little explanation. You learn by dying, again and again, until an enemy that wrecked you becomes routine. The mood is decline: kings gone mad, gods fading, fires going out.