This "impossible" Yu-Gi-Oh speedrun can take three days to complete and only has a 3% chance of being viable, and after 25 years only 100 people have done it in under 9 hours

gamesradar.com:

This "impossible" Yu-Gi-Oh speedrun can take up to three days to complete and only has a 3% chance of actually being viable. 

Yu-Gi-Oh Forbidden Memories may have been released in 1999, but players are still struggling to beat it in record time 25 years later. As highlighted by YouTuber CDawgVA, it's almost "impossible" to speedrun the virtual card game, despite it being fairly beginner-friendly due to it not following the card game's official rules.

At the time of writing, there are plenty of ways to set records by speedrunning this game, including Any%, Any% New Game+, and 100% - which involves getting all 722 cards in the game. There are also two subcategories: with and without RNG (Random Number Generator) maps. As you'd expect, the results vary on speedrun.com with the quickest time being just under 38 minutes, and the longest taking over three days to fully complete. 

To help put this into perspective, here's a rough idea as to why this game is so darn difficult to beat in record time: As explained in the video below, you really do have the odds stacked against you in Yu-Gi-Oh Forbidden Memories. Not only do you start with a "garbage" starter deck - part of the reason why you've only got a 3% chance of finding a viable seed at the start of each run - but enemies will usually have stronger cards than you and, in terms of the final boss, will know what cards you're going to play.

This already sounds difficult but it gets worse when you discover that the final boss is actually six final bosses which all need to be beaten. If you lose to any of them, you'll also be sent back to the first one and need to battle your way through all over again. In terms of the cards you're dealt, it's apparently a long and exhausting process to get anything good. 

According to CDawgVA, every time you beat an enemy, you get a card drop, and "90%" of them are terrible. Since the good cards have a very low drop rate, you're also forced to grind through enemies to make any progress.