Super Mario Maker 1 is a level creation game / tool released by Nintendo for the Wii U in 2015. It's been bought over 7.5 million times, and has had thousands upon thousands of levels created.
Sometime around 2021, Nintendo ceased the ability to upload new levels to Mario Maker 1 (Mario maker 2 had been out for a couple years at this point)
In comes Team 0%. This team had existed for a bit already, as a team that wanted to make sure there was no unbeaten levels in Mario maker 1 and 2. With the news of no more levels for the original, the goal was actually attainable for the first time ever.
Fast forward to October 2023, Nintendo announces all online functionality will cease for 3ds and Wii U titles in early April (specifically April 8th 2024). Now Team 0% had a time limit to finish. Many highly skilled Mario maker players came together to try and "beat" the game.
Well as of an hour or so ago, the second to last level, a New Super Mario Bros style level called "The Last Dance" was cleared by japanese player Yamada as seen here
https://youtu.be/roIFvn569VI?si=4z1AF7WN8zxNHIdS
So.... One level left. The community has a few weeks to finish it. Is it hard? Well..... I'll let ThaBeast721 (a very skilled player who has completed a fair number of these last levels) explain the level:
https://youtu.be/KmikpEVCuZE?si=uNbXhV1QplXVJVh5
So, it's really hard. But the end is in sight. Mario Maker 1 is one level away from being fully beaten!