Super Mario Bros.: The Lost Levels is the original sequel to Super Mario Bros. and was only released in Japan. The game was very difficult and for this reason it wasn't released elsewhere. instead a similar but much easier and less infuriating game, known to the US/EU as Super Mario Bros. 2. was created.
The game was released outside of Japan on the Virtual Console in September but will only be available until the end of September 2007, that is the end of today. If Nintendo stick to their promise exactly; it will be gone in one hours time in fact (GMT). So if you want to get it, fire up your Virtual Console page, get some points before it is too late.
It will cost you 600 points.
Sorry about the late warning but this one escaped us here at NintendoLife but hopefully you will get there in time.