Not to be confused with World 2 (which is the one you start with)
World 1 is the sixth and final World in Braid. The fact that World 1 is the last World, as opposed to the first, symbolizes the time-twisting nature of the game. It also shows that the game ends with the beginning of the story.
World 1 is located in the attic of Tim's House, and can only be accessed when all puzzles of all other Worlds have been completed. Because of this, there are no puzzle pieces and thus no puzzle for World 1, and the goal of all its levels is to reach the exit.
Also, the doors in World 1 are available in reverse, i.e. the door on the far right is unlocked first and the left-most door is unlocked last.
In World 1, time flows backwards. Everything happens in reverse, although, like World 4, Tim is not bound to this rule. Therefore, if Tim reverses time, his actions are done in reverse, but everything else appears to be flowing normally.
At a cafe on a bright plaza, most customers sit back, feeling the warmth of the sun, enjoying their cold drinks. But not Tim — he barely notices the sun, doesn't really taste his coffee. For him this corner affords a good view of the city, and in the teeterings of the passers-by, in the arc of a shop-girl's hand as she displays tea to an interested gentleman, Tim hopes to see clues.
That night at the cinema, fictitious adventurers lunge implausibly across the screen. The audience here is mixed. Some are patrons of the cafe, now sitting excitedly in the plush chairs, eager for another new flavor, for distraction from the boredom of their easy lives. Other seats hold fishermen and farm-workers, hoping to forget their toils and rest their hands.
Tim is here too, but he is scrutinizing the gloss on the lips on the screen, measuring the angle of the plume of a distant helicopter crash. He thinks he discerns a message; when the cinema closes and most of the audience strolls down the plaza to the South, Tim goes North.
People like Tim seem to live oppositely from the other residents of the city. Tide and riptide, flowing against each other.
Tim wants, like nothing else, to find the Princess, to know her at last. For Tim this would be momentous, sparking an intense light that embraces the world, a light that reveals the secrets long kept from us, that illuminates — or materializes! — a final palace where we can exist in peace.
But how would this be perceived by the other residents of the city, in the world that flows contrariwise? The light would be intense and warm at the beginning, but then flicker down to nothing, taking the castle with it; it would be like burning down the place we've always called home, where we played so innocently as children. Destroying all hope of safety, forever.