YouTuber Marcel Vos built this "impossible maze" in Roller Coaster Tycoon 2 that takes 6.6*10^19,758 years to complete. If you don't understand how big that number is, it's a 6 followed by about twenty thousand zeroes. And if you don't understand how big that number is, it's okay because nobody does. It's incomprehensibly large.
The maze itself is not very impressive, but exploits the pathfinding algorithm for guests in the game. Marcel starts out with an explanation of the exploit using a smaller version of his maze and then slowly scales it up. You can skip to 7:30 to see the progression and then at about 7:40 he reveals the completed maze. Just looking at it gives me PTSD of the time I got lost in a corn maze. And by corn maze I mean the time I got lost in the canned corn section of the supermarket when I accidentally held on to the wrong woman's hand. "Wasn't that, like, last week?" Yes. Yes it was.
NOTE: Less than 48 hours after Marcel published his video, OpenRC2 (an open source re-implementation of Roller Coaster Tycoon 2) patched the pathfinding algorithm to not prefer a direction and the commit literally says: "This is just to mess up MarcelVos"
Keep going for the full video and the math-heavy explanation of how the maze works.