Actually, Wario's Castle is also a big maze, so Mario needs to find his way to Wario before they can have their epic clash. Info on next issue below:
Spoiler Below The next comic (either part of it or all of it, haven't decided) will detail where exactly Wario is and what he's been doing since he last played cards with Mario (#14). Also, he will look different than before, and the comic will explain why...look forward to next Tuesday!