Any excuse.

Wario, Luigi, Peach: they've all had chances to strike out on their own with games where they play the lead, but one character missing from the line-up is lanky misfit Waluigi, who's yet to receive his own game. At least one person sees the injustice in this situation: voice actor Charles Martinet, who sees the purple potential:

I'd love to see a Waluigi game where you have to cheat to win, ya know. That would be funny.

Mr Martinet made a similar remark to us in October, so it seems it's not an off-the-cuff idea but something he actually would like. Maybe he's voiced his opinion to Nintendo and they're thinking about it. Who knows? Speculation aside, you don't have to wait for a Waluigi game where cheating equals winning: certain staff here have made that an artform already.