The archive · Developer & Business Tools · Product decision · 2018–2020
MockMechanics bets mechanical programming needs physical intuition, not syntax; HN 719
A solo Clojure sandbox where tracks, levers and chips behave like programs drew 719 HN points in 2020; users saw the next Minecraft, no category yet.
MockMechanics
What the business is
MockMechanics is a downloadable 3D sandbox, written in Clojure by one developer, where you build mechanical contraptions — tracks, wagons, levers, chips and short scripts — that behave as programs: a working piano built in minutes, a Tetris machine in half an hour, with machines importable as parts of bigger machines.
How it started
The author, posting as felipereigosa, said the seed was a college-era urge to formalize mechanical devices — how to describe machines the way chess and dance have notations — and that his first commit to MockMechanics was 2018-03-30, after an earlier 2D attempt went nowhere. He built it in Clojure with a jbullet physics engine, and on 2020-10-29 posted a Show HN titled 'What would mechanical programming look like?', honestly unsure whether he had made a game, a game engine, a 3D editor or a visual programming language, and asked people to try it and show him what was possible.
What happened
The thread drew 719 points and 149 comments. Praise was unusually strong — 'one of the best show HNs I have seen in quite a while', 'you are sitting on the next minecraft' — and users tested it with children, asked for source and a licence, and reported a macOS crash the author could not reproduce without a Mac. Commenters mapped the prior art: Working Model, The Incredible Machine, ThingLab, Garry's Mod Wiremod, Opus Magnum and MathWorks Simscape Multibody. The author spent the thread clarifying the bet: machines compose like software, a track doubles as a motor, buttons exist only for convenience, and the goal is to exploit people's built-in physical intuition; he started a Patreon mid-thread after a commenter pledged $100, built a music-box machine the next morning and posted it, and said he was weighing open-sourcing against releasing a paid Steam game.
No ending yet — it is still running.
Background
MockMechanics is a 3D sandbox where mechanical contraptions are programs. Built alone in Clojure over roughly two and a half years, it lets you assemble tracks, wagons, levers and chips with no code editor; a piano works in minutes and a Tetris machine in half an hour, and machines can be imported as parts of larger machines, like functions composed into bigger programs.
The origin was a question, not a market. The author, felipereigosa, wanted to know what programming would look like if it were mechanical — inspired by an urge to formalize machines the way chess and dance have notations — and posted on 2020-10-29 a Show HN titled 'What would mechanical programming look like?', admitting he was not sure whether he had built a game, an engine, an editor or a language.
Hacker News answered with 719 points and 149 comments, several calling it the best Show HN of the year and the next Minecraft. The scrutiny mapped a crowded field of prior art — Working Model, The Incredible Machine, ThingLab, Garry's Mod Wiremod and Simscape Multibody — while users hit a macOS crash and asked for open source; the author said he needed Patreon-style support first, created a Patreon mid-thread after a $100 pledge, and weighed a paid Steam game against open-sourcing.
The material documents no outcome beyond the thread: one developer, an adored toy, downloads and a Patreon, with the category and the business model still unresolved when the record ends.
What has to be true
- The bet was aesthetic before commercial: exploit people's built-in physical intuition so that building a machine feels like solving a puzzle, not writing code.
- Composability was the power move: machines built by one user become parts for another's larger machine, turning the sandbox into an ecosystem before it had users.
- The author deliberately simplified — a single numeric state per part, a track doubling as a motor — and said that when in doubt he went simpler, which is what commenters said they loved.
- The response proved appetite without proving a business: schools, kids and sandbox fans all said yes, but nobody in the thread named a buyer.
What can be applied
An exploratory answer to a what-if can find an audience long before it finds a category: people rallied around the toy, but the maker still had to name what it was and who would pay.
Aftermath
As of the 2026-09-05 crawl, the material is the 2020-10-29 HN thread itself: it records 719 points and 149 comments, a downloadable Clojure sandbox, an author weighing open-source against a paid Steam release, and a Patreon created mid-thread after a supporter pledged $100. Nothing in this material shows what happened to MockMechanics after 2020, so its later state is not recorded here.
Sources
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