By ByteBot
Tomorrow (December 1, 2025), Advent of Code launches its 11th year with changes that break a decade of tradition. The beloved coding challenge event drops from 25 days to just 12, and the global leaderboard is gone forever. Creator Eric Wastl didn’t sugarcoat it: after 10 years of exhausting 25-day marathons, he chose sustainability over ritual. The culprits? Creator burnout, AI-powered solvers completing puzzles in under a minute, and DDoS attacks from competitors. This isn’t AoC dying—it’s adapting to reality.
The Changes Are Dramatic
Advent of Code 2025 runs December 1-12, not through Christmas Day. That’s 12 daily puzzles instead of the traditional 25 that matched the advent calendar format. The global leaderboard—which ranked the fastest solvers worldwide—is permanently discontinued after 10 years.
However, what’s preserved matters. The event remains free. Puzzles still release daily at midnight EST. Private leaderboards for friend groups and communities still work. You can still solve in any programming language. The core experience—challenging yourself with creative coding puzzles—hasn’t changed.
According to the official 2025 announcement, “The puzzles still start on December 1st so that the day numbers make sense (Day 1 = Dec 1), and puzzles come out every day (ending mid-December).” The format changed, but the spirit didn’t.
AI and DDoS Attacks Killed the Leaderboard
Wastl didn’t mince words about why the global leaderboard died. Top solvers were completing puzzles “in less than a minute” using AI assistance. Meanwhile, competitive players resorted to DDoS attacks on the infrastructure to prevent rivals’ scores from updating.
“The global leaderboard was one of the largest sources of stress for me, for the infrastructure, and for many users,” Wastl explained. “Some people took things too seriously, going way outside the spirit of the contest, even resorting to things like DDoS attacks.”
Moreover, the leaderboard became pointless. When LLMs can solve coding puzzles faster than humans can read the problem statement, speed rankings lose all meaning. Wastl’s stance on AI is clear: “If you send a friend to the gym on your behalf, would you expect to get stronger? Advent of Code puzzles are designed to be interesting for humans to solve.”
This mirrors competitive chess after AI. Humans stopped trying to beat Stockfish and focused on human-vs-human play. Global speed competition in coding is dead. AI killed it.
Creator Burnout After 10 Years
The 12-day format addresses the other elephant in the room: Wastl’s exhaustion. “It takes a ton of my free time every year to run Advent of Code, and building the puzzles accounts for the majority of that time,” he wrote.
Creating 25 clever, original coding puzzles annually—for 10 straight years—is unsustainable. Add infrastructure stress (DDoS attacks, traffic spikes, leaderboard gaming), and you get burnout. After maintaining a “consistent schedule for ten years,” Wastl needed a change.
Importantly, he chose to scale back rather than quit entirely. This is the healthy response. Too many open-source creators burn out in silence, then suddenly abandon projects. Wastl said, “Here’s what I can sustain,” and adjusted. The event survives because the creator prioritized long-term viability over tradition.
Community Reaction Is Supportive
Developers aren’t mourning the changes. They’re relieved.
One backend services developer commented, “Honestly, this makes it easier to participate.” The reality is that 25 straight days during the holiday season—with family gatherings, travel, and end-of-year work crunches—was brutal. Many participants burned out by mid-December.
Furthermore, the leaderboard removal got support. “Welcomed the changes and thought the global leaderboard should’ve gone a few years ago when LLMs started being a thing,” one developer noted. The community recognized that AI made competition meaningless.
According to BigGo News coverage, “Mostly, the community just seems grateful that their December tradition continues.” The Hacker News discussion (221 points, 76 comments) reflected the same sentiment: sustainability beats rigid tradition.
Programming language communities remain fully engaged. Kotlin is hosting daily livestreams with prizes. Scala promoted participation. Alteryx organized their community. The event is healthy, not diminished.
What This Signals About Competition Culture
The shift from 25 to 12 days and from global to private leaderboards represents a broader cultural change in programming.
Global competition became toxic. Players DDoS’d infrastructure. AI contaminated rankings. Many developers felt inferior because they couldn’t match minute-long AI-assisted solves. As Wastl noted, “Many people incorrectly concluded that they were somehow worse programmers because their own times didn’t compare.”
Meanwhile, private leaderboards—where you compete with friends and colleagues—stay healthy. Social competition works. Anonymous global speed rankings don’t.
This pattern repeats across tech. AI killed speed-based rankings in chess, writing, and now coding. What survives is the human element: learning, creativity, community. AoC’s changes recognize this reality.
The sustainability model matters beyond Advent of Code. Free community projects face creator burnout constantly. Wastl’s response—reduce scope before you break—should be the standard. It’s better to run 12 sustainable days than 25 exhausting ones.
Tradition Adapted for Reality
Advent of Code 2025 proves that tradition isn’t sacred when it’s unsustainable. After 10 years of 25-day marathons, Wastl chose creator well-being and long-term survival over rigid format adherence.
The community responded with support, not backlash. Developers value the event and its creator more than arbitrary day counts. They recognize that AI-contaminated global leaderboards were meaningless. They appreciate that 12 days during the holidays is more realistic than 25.
This is what healthy adaptation looks like. The core value—challenging yourself with creative coding puzzles—remains intact. The toxic elements (global speed competition, creator burnout) got cut. The result is an event positioned to last another 10 years, not one barreling toward shutdown.
Tomorrow, thousands of developers will open their first puzzle of Advent of Code 2025. They’ll compete with friends, learn new techniques, and enjoy the tradition. Just for 12 days instead of 25. And that’s perfectly fine.
