I'd like to see a Mario and Yoshi tag-team type game, sort of like the tag-teams in the DKC games. You could choose between Mario being in control and having Yoshi follow him, or have Mario ride Yoshi who will be in control. Mario would have his usual powerups, abilities, and items (perhaps even the suits from SMB3), and Yoshi would have his abilities and items from Yoshi's Island. There would be areas, objectives, items, etc. that could only be obtained/completed if you were a particular player. You would need to switch often in order to get 100% in the game, and also to finish certain levels and beat certain bosses (particlarly later in the game). This game would be lengthy, innovative, diverse, and at the same difficulty level as the NES/SNES Mario games (not short, easy, and half-a**ed like Yoshi's Story). Koji Kondo should do the music. And for 2-player mode, the second player's tag-team would be Luigi and a red Yoshi.