This was Ready Player 50

Carter Zenke, Yuliia Zhukovets, David J. Malan

10 min readOct 5, 2023

Quack. Ready Player 50 is a wrap! Ready Player 50 brought together participants from over 116 countries. Read on for our reflection (and a few fun photos and memes!) on the event, a collaboration with the AI security company Lakera and an adaptation of their famous prompt-injection game, Gandalf. If you participated this past weekend, we’ll share more secrets here than the CS50 Duck did!

As background, Ready Player 50 brought over 10,000 participants to, where they competed to get the CS50 Duck to reveal its secret password through seven increasingly difficult levels. At each level, participants entered a “prompt” to the CS50 Duck (who is, in fact, a large language model, or LLM!) to try to bypass its various defenses and trick the duck into revealing its password. In all levels except level one, that is. In that level, you might recall, the CS50 Duck was defenseless!


Over 5,000 people registered for Ready Player 50 and over 10,000 participated at At the end of the event, approximately 3,100 players submitted their answers. Among the submissions were:

  • 830 from the United States
  • 471 from India
  • 153 from the United Kingdom
  • 138 from Canada
  • 97 from Singapore
  • 79 from Brazil
  • 79 from Germany
  • 65 from Pakistan
  • 47 from Poland
  • 46 from Iran


Of the 3,139 participants who submitted their answers to us, 2,945 participants passed all 7 levels! That’s a whopping 94%. Happy to say, too, that 3,104 participants (or 99%) solved at least 2 levels! If you’re curious to see a walkthrough of some of the (many!) potential solutions, watch our solution walkthrough with Natalie and Max from Lakera.

Along the way we took a souvenir photo with those who attended live.

And special thanks to Sophie Anderson for the event’s artwork! Check out her artwork at Sophie’s storefront.


Glad to say that, among those who submitted, 61% claimed to have “loved” Ready Player 50! Another 34% claimed to have liked it. The CS50 Duck would be proud.

We also asked participants about their favorite level, which turned out to be level 6 by a wide margin!


Want to try your hand at Ready Player 50? The fun lives on at, so don’t be afraid to test your mettle against the CS50 Duck’s defenses! And for those who participated during the weekend event, conquering all 7 levels, CS50 Certificates were awarded, stamped by the CS50 Duck!

What’s next? Besides being ridiculously fun, Ready Player 50 was the perfect prelude to our newest course: “CS50’s Introduction to Cybersecurity”, available for free at If you liked Ready Player 50, you’re going to love diving deeper into the world of cybersecurity with us.

See the below for some photos and memes from participants!


Of particular note were the photos of players around the world coming together to player Ready Player 50!


The memes shed some light on the humorous side of cybersecurity!




Harvard University’s introduction to the intellectual enterprises of computer science and the art of programming.