The original "Super Mario Bros." for the Nintendo Entertainment System (NES), released in 1985, is one of the most iconic video games of all time. The game is structured into eight distinct worlds, each consisting of four levels, commonly referred to as stages. This brings the total to 32 levels in the entirety of the game. Here's a breakdown of the worlds and their corresponding stages: - **World 1**: Overworld, Underground, Overworld (with a repeat of the iconic first level's design), and Castle - **World 2**: Overworld, Underwater, Overworld, and Castle - **World 3**: Overworld (night), Overworld (with platforms and jumping Cheep Cheeps), Overworld (night), and Castle - **World 4**: Overworld, Underwater, Overworld, and Castle - **World 5**: Overworld (winter), Underground, Overworld (winter), and Castle - **World 6**: Overworld (autumn), Overworld with a Lakitu throwing Spiny eggs, Overworld (autumn with more enemies and obstacles), and Castle - **World 7**: Overworld, Overworld with Lakitu and Bullet Bills, Overworld (maze-like with repetitive structures), and Castle - **World 8**: Overworld (filled with hazards, no power-ups), Underworld (lava-themed), Overworld (tank and cannon arrays), and Castle/Castle Dungeon (the final challenge leading to the final boss battle with Bowser) Each level has its own unique challenges, enemy types, and game-play mechanics. The level design becomes progressively more challenging as the player advances through the game. The "Overworld" and "Castle" levels appear in each world, but the environments and difficulties change. For example, "Underground" levels will usually have enclosed spaces with plenty of pipes and breakable blocks, while "Underwater" levels feature swimming mechanics and aquatic enemies. In addition to these standard levels, there are also a number of hidden Warp Zones found within the game that allow players to skip ahead to later worlds, typically accessed by discovering secret areas within certain levels. The various enemy types, platforming challenges, and the game's music and sound effects all contribute to the enduring popularity of "Super Mario Bros." Its levels and game design principles have been studied and admired by game developers and players alike, remaining influential and relevant even decades after the game's initial release.