A fun sequel to Mario & Luigi with a great premise that's used very well. Traveling back to the past to the time of an alien invasion a lifetime prior was a great conceit, and adding Baby Mario and Baby Luigi on X and Y was a great gimmick. The Bros Item system was also a neat innovation, bringing more gameplay possibilities than Bros Moves did previously. While parts of the game did drag a little, I still think this is one of the best of the Mario & Luigi series.