Mario Adventure is a fan-made alteration of Super Mario Bros. 3. Its author DahrkDaiz single-handedly made new maps and levels from scratch, so it's sort of like "The Lost Levels" from Super Mario All-Stars, except done on Super Mario Bros. 3 and not made by Nintendo.
Like The Lost Levels, Mario Adventure is hard. In fact, you’ll have to be able to beat SMB3 proficiently before you can really sink your teeth into this game. The game provides a spare-box, lots of power-ups, and some powerful items, but the game is full of intense and well-thought-out levels, some of which will require you to build and refine strategies to complete.
The game and a NES Emulator are available from this article.