Nice opening
I see that you know your way around Flash. The smooth animations and custom sprites were amazing. The sound effects were played correctly and the music was really effective for setting the mood. The title screen and Scene Selection screen were both very well-done. The plot is very original, too (as opposed to most other Mario sprite animations, which are usually just "Mario dies and Luigi gets revenge" type things). I can't wait for the sequel to come out. If you apply as much work to that one as you did to this one, then it'll be great. Excellent work.