One Year of Vibe Coding: From Levelsio's Flight Sim to a $285 Billion Selloff

On February 22, 2025, indie maker Pieter Levels — known online as @levelsio — sat down with Cursor, an AI-powered code editor, and told it to build a flight simulator. He had never made a game before. Three hours later, fly.pieter.com was live. Within 17 days it was generating $87,000 per month. Within a year it would become the most cited example of a phenomenon that Andrej Karpathy had named just three weeks earlier: vibe coding.

Now, twelve months on, fly.pieter.com is still running, still profitable, and the movement it helped ignite has triggered a $285 billion selloff in software stocks. This is the story of what happened in between.

What Levelsio Actually Built

fly.pieter.com is a free-to-play, massively multiplayer 3D flight simulator that runs entirely in the browser. Players take off from real-world airports, fly over a stylized version of Earth, and see other players in real time. It was built with Cursor using Claude as the underlying model, with ThreeJS handling the 3D rendering. The entire codebase is vanilla HTML and JavaScript — no frameworks, no build tools, no backend complexity.

The original launch tweet set the tone:

“Ok it’s done, you can play it at fly.pieter.com. I’ve never ever made a game before and just made my own flight simulator 100% with Cursor in I’d say 3 hours by just telling it what I wanted.”

What made it remarkable wasn’t just the speed of development — it was the business model that emerged. Levels monetized the game through in-game advertising blimps (floating billboards purchased by companies at roughly $5,000/month each), premium plane skins like an F-16 fighter jet at $29.99, and branded 3D objects placed in the game world.

The Revenue Ramp

The numbers escalated fast:

Timeline	Monthly Revenue	Milestone
Day 1	$0	Launch
Day 10	$38,360	19 blimps sold, 16,000 daily players
~3 weeks	$67,000	320,000 total players
Day 17	$87,000	$1M annualized
November 2025	$138,000	70% of Levels’ total income

By day 10, Levels was posting granular revenue breakdowns on X: “19x Blimps sold at various prices = $38,000/mo + 12x F16’s sold @ $29.99 = ~$360 = $38,360/mo.” By day 17, he announced $1 million in annualized revenue — calling it “my first project ever to go up this fast.”

Nine months later, the game was still generating $138,000 per month, making it the single largest revenue source in Levels’ portfolio of indie projects.

The Copycats Arrived Immediately

Success brought imitators. Within days of fly.pieter.com going viral, clones began appearing — other browser-based flight games and simulators, many also built with AI tools. GitHub repositories like vibe-jet (built with Gemini) appeared. An AI-built Call of Duty-style shooter, endorsed by Elon Musk on X, went on to generate $12,000/month in revenue.

Rather than fighting the copycats, Levels channeled the energy. On March 18, 2025, he announced the Vibe Coding Game Jam at jam.pieter.com — a competition where at least 80% of code had to be AI-generated, and games had to be web-based, free-to-play, and multiplayer with no login required.

The response was massive: over 1,170 games were submitted. Levels and his judges hand-vetted more than 1,000 entries, cutting to roughly 500 finalists. The winning submissions — announced in April 2025 — included a GTA-style taxi simulator, an air traffic control game, and a bot automation challenge. Prizes totaled $17,500, sponsored by Bolt and CodeRabbit.

The game jam did something the copycats alone couldn’t: it turned vibe coding from a solo novelty into a community with shared norms and creative output.

Other Viral Vibe Code Projects

fly.pieter.com was the spark, but 2025 produced a string of projects that proved vibe coding wasn’t a one-hit wonder.

Qconcursos: $3 Million in 48 Hours

Brazilian ed-tech company Qconcursos used Lovable to rebuild their premium education platform. Two developers replaced a team of 30 and rebuilt the product in two weeks instead of the year it would have taken traditionally. The platform — which included a database of 4 million questions and AI-powered photo-upload assistance — generated $3 million in revenue in its first 48 hours after launch.

Y Combinator’s AI-Generated Batch

In March 2025, TechCrunch reported that 25% of Y Combinator’s Winter 2025 batch — roughly 40 out of 160 companies — had codebases that were 95% or more AI-generated. YC managing partner Jared Friedman clarified that every founder was “highly technical, completely capable of building their own products from scratch. A year ago, they would have built their product from scratch.” They chose not to.

The W25 batch went on to become the fastest-growing and most profitable cohort in YC’s history, growing 10% per week in aggregate.

The CNBC Monday.com Clone

On February 5, 2026, CNBC reporters with no coding experience used Claude Code to build a functioning Monday.com replacement — complete with project management, calendar integration, and email connectivity — in under an hour for roughly $5-15 in compute credits. Monday.com has a $5 billion market cap. The segment aired during a week when software stocks were already in freefall.

The Indie Hits

A wave of smaller projects proved that vibe coding could generate real, sustainable businesses:

Disko (Iceland): Built with Replit, an SMS messaging service that hit $11K monthly revenue in four months and is expanding globally.
ChatIQ: An AI customer support tool built by a non-technical founder, reaching 11,000+ users and $2,000 monthly revenue.
PrintPigeon: A physical mail SaaS built in three days by a digital marketer with zero coding experience, using Lovable.

The Movement Behind the Projects

The projects were symptoms of something larger. Here’s how the broader vibe coding movement unfolded:

February 2025: The Name

On February 2, 2025 — twenty days before fly.pieter.com launched — former Tesla AI director Andrej Karpathy posted on X:

“There’s a new kind of coding I call ‘vibe coding’, where you fully give in to the vibes, embrace exponentials, and forget that the code even exists.”

The term stuck instantly. It captured something developers were already experiencing with tools like Cursor and Claude Code — the shift from writing code to directing an AI that writes code for you.

Spring 2025: Mainstream Breakthrough

March brought the YC revelation, the game jam, and fly.pieter.com crossing $1M ARR. Lovable raised a $200M Series A at a $1.8 billion valuation. Merriam-Webster added “vibe coding” as a trending term. The phrase escaped tech Twitter and entered the broader conversation.

May 2025: The Security Reckoning

The backlash was inevitable. In May, security researcher Matt Palmer published CVE-2025-48757, documenting critical vulnerabilities in Lovable-generated apps. Out of 1,645 Lovable-built apps he examined, 170 had exposed databases containing emails, phone numbers, payment details, and API keys — all due to missing row-level security. Palmer had reported the issue to Lovable on March 21; it took over two months for a partial fix.

The vulnerability highlighted a real tension: vibe coding tools optimized for speed of creation, but security required a depth of understanding that “forgetting the code even exists” made harder.

September 2025: The Hangover

By fall, a more nuanced picture had emerged. Fast Company published “The vibe coding hangover is upon us,” documenting the technical debt accumulating in AI-generated codebases. A PayPal senior engineer described a growing maintenance burden. Stack Overflow’s survey found 46% of developers distrusted AI coding tool accuracy. Reports circulated that 45% of AI-generated code contained security vulnerabilities of some kind.

None of this slowed adoption. It did, however, clarify who vibe coding worked for (prototypes, MVPs, indie projects, internal tools) and where it struggled (large-scale production systems, security-critical infrastructure, long-lived codebases).

November 2025: Word of the Year

On November 6, Collins English Dictionary named “vibe coding” its 2025 Word of the Year. In the same month, Lovable crossed $200M in annualized revenue. fly.pieter.com was generating $138K/month. The cultural and economic footprints were undeniable.

January 2026: Even Linus Torvalds

In a moment that surprised even hardened skeptics, Linus Torvalds — the creator of Linux and Git — used Google Antigravity to vibe code the Python visualization component of his AudioNoise project (a random audio effects generator). His README noted: “I cut out the middle-man — me — and just used Google Antigravity to do the audio sample visualizer.”

When the person who created the tools that most of the world’s software runs on starts vibe coding, the practice has moved past novelty.

February 2026: Wall Street Takes Notice

The first week of February 2026 brought the culmination. Anthropic’s Claude Cowork launched plugins for legal, finance, and product workflows. Software stocks lost $285 billion in a selloff. The iShares Expanded Tech-Software Sector ETF (IGV) fell 29% since the start of January — the worst two-month stretch since 2008. CNBC’s Monday.com clone aired. Anthropic released Opus 4.6.

And on February 4, exactly one year and two days after his original tweet, Karpathy posted a retrospective declaring that vibe coding was evolving into “agentic engineering” — a practice where developers manage multiple AI agents that generate, debug, and refine code in parallel, with the human role becoming strategic oversight rather than hands-on implementation.

What a Year Tells Us

The trajectory from fly.pieter.com to a $285 billion stock selloff was not linear, and it wasn’t entirely predictable. But looking back, the pattern is clear:

Phase 1 (Feb–Apr 2025): Proof of concept. Individual creators like Levels showed that AI tools could produce functional, monetizable software in hours. The game jam proved it was repeatable.

Phase 2 (May–Sep 2025): Growing pains. Security vulnerabilities, technical debt, and maintenance challenges emerged. The tools got better, but so did the understanding of where they fell short.

Phase 3 (Oct 2025–Feb 2026): Market impact. Vibe coding stopped being a developer curiosity and became a force that Wall Street, enterprise software companies, and legacy tech incumbents had to reckon with. Lovable went from $7M to $200M+ ARR. Monday.com launched “monday vibe” as a defensive move. Software stocks repriced.

fly.pieter.com is still running. Pieter Levels is still shipping. And the 3-hour flight simulator that started as a side project has become the most concise illustration of what changed in software development in 2025: the barrier between idea and product got lower than anyone expected, faster than anyone predicted.

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