Pencil Code is a collaborative programming site for drawing art, playing music, and creating games. It is also a place to experiment with mathematical functions, geometry, graphing, webpages, simulations, and algorithms. Programs are open for all to see and copy.
Watch a video overview or watch a video tutorial.
The main language is Coffeescript. Professional software engineers use Coffeescript to build complex websites, but Coffeescript code can also be very simple.
Pencil Code can also be used to explore and learn Javascript, HTML, and CSS: when you are ready, just find the "gear" button to adjust languages.
Programs preload the pencilcode library to use turtle graphics functions. Pencil Code is all open source. Hang out on the Pencil Code discussion forum or check out the quick reference or the online guide to find out more. There is also an illustrated Pencil Code book with more than 100 small projects.
Anybody can save programs and web pages, but read the Terms of Service and the Privacy Policy first. Two rules:
Be Nice. Do not mess up other peoples' work. Do not post content that detracts from education on the site. This a learning space that is not locked down (for example, passwords are optional). So feel free to explore, create, and link, but also please be considerate.
Be Careful. Do not depend on Pencil Code to keep your data safe. Data posted here is public, and data is not secured from loss. Do not post private or personally identifiable information. Passwords on Pencil Code do not prevent malicious interference.
The Pencil Code Foundation is devoted to advancing computer science education by making programming as simple and as universal as using a pencil. Contribute to the development of Pencil Code at dev.pencilcode.net or github. — .
What followed over the next 72 hours was a compact masterclass in crisis engineering:
Bella’s leadership mattered less in this phase than the team’s willingness to be brutally honest. No excuses, only forensic clarity and an appetite for iteration.
Bang & Burn: Mission 001 returns in its definitive Patched Edition — a complete rework of the explosive opening chapter of Bella Spark’s high-octane action series. Originally plagued by progression-breaking bugs, unbalanced enemy spawns, and physics glitches that turned flame effects into blinding strobes, this patched version rebuilds the mission from the spark up. bella spark bang and burn mission 001 patched
The first ignition performed almost perfectly: a starburst of controlled plasma, the coils singing like cathedral pipes. The second pulse, however, encountered an unexpected resonance in the platform’s cooling matrix. A microfracture—hairline, microscopic—propagated under stress from repetitive thermal cycling. The result was a delayed venting that skewed the third pulse trajectory. The micro-fusion plume kissed the safety shroud and produced a localized burn pattern that charred a telemetry array and sent a shower of molten slag into the platform’s outer skin.
No one died. No catastrophes beyond reputational damage. But “Mission 001: Bang and Burn” had become Mission 001: Patch Required. What followed over the next 72 hours was
“Patched” didn’t mean fixed forever—it meant improved, hardened, and socially accountable. Media had a field day with the charred telemetry array images, but the follow-up narrative was more interesting: a transparent log of failure, the publication of a detailed incident report, and an open-sourced portion of the mitigation firmware. That move turned potential ire into unexpected trust. Clients and regulators saw a company that accepted fallibility and, crucially, learned in public.
Technically, Mission 001’s patch accomplished three things: Bella’s leadership mattered less in this phase than
For Bella, the episode became a pivot point. She had always trusted the math; now she trusted the team’s capacity to change it. The scars on the platform’s skin became a quiet emblem—an engineering memento that success is often built from well-documented mistakes.
Prominent speedrunner PyroVortex tweeted shortly after the patch: “RIP Mission 001 Any%. The Sparksurge loop was the only thing making that mission bearable. Now it’s a slog of waiting for burn ticks.”
The removal of the infinite AP loop means the fastest possible completion time is now estimated at 4 minutes and 22 seconds—assuming perfect RNG. The leaderboards have been wiped for the “Exploit” category, and a new “Patched” leaderboard has been created. Many speedrunners have already moved to Mission 003 as the new meta category.