Son of Super Mario illustrated fan-fic

A kid from Bay Ridge, Brooklyn wandered the underbelly of New York. He had found the derelict chamber known as the "Warp Zone" pretty quickly. The map left by his uncle Luigi made the sewer system easy to navigate. The inscriptions on the pipes were vague. What was world 1-1? He found out soon enough. The Warp dropped him off in a strange landscape overrun with toadstools (some of them sentient). An entire microverse existing perpendicular to New York. Now all he had to do was follow Luigi's instructions. Climb the stairs at the far end of the world, jump off the top and tag the flag in front of the castle. It sounded simple enough. But was it?