Questions

Each answer has its own link, so a single one can be shared directly.

What is Cortex?

Seven puzzles, each training a different kind of thinking: sequencing a robot's instructions, holding a sequence in working memory, deducing an arrangement from clues, routing a network so nothing leaks, inferring the rule behind a row of figures, reaching a target number, and playing a phrase back by its intervals. Every puzzle has eight levels that get harder as you go.

Is this The Lost Mind of Dr. Brain?

No. Cortex takes its shape from that 1995 Sierra On-Line game — a collection of puzzles each exercising a different mental skill — and nothing else. It shares no code, art, audio, text or characters with it, and it is not affiliated with or endorsed by the rights holders. If you want the original, buy the original.

Do I need an account?

No, and there isn't one to make. Cortex has no server, no login and no sync. Your progress lives in this browser on this device.

What does it store about me?

Which levels you have solved, your best score on each, and your settings — language, theme, sound, and whether you have seen the first-run tour. All of it in this browser's own storage, none of it leaving the device. The cookie policy lists every key.

Nothing is written until you actually do something. Opening the page and reading it stores nothing at all.

How do I delete my data?

Settings → Your data → Erase all progress. It is immediate and complete. You can also download everything Cortex holds as a JSON file from the same place.

Does it work offline?

Yes, once you have opened it at least once. Cortex caches itself on the first visit and plays with no connection afterwards. There is nothing it needs the network for.

Can I put it on my home screen?

Yes — see the install walkthrough, which has the steps for iPhone, Android and desktop. Installing gives you an icon, a full-screen window with no browser bar, and offline play. It stores nothing extra.

I am stuck on a level. Is it definitely solvable?

Yes, and that is checked rather than claimed. Every level of every puzzle is verified by an automated search before the build is allowed to pass: Circuits levels by finding the shortest working program and confirming it fits the instruction budget, Deduction puzzles by proving exactly one arrangement satisfies the clues, Pathways grids by confirming they form a complete network, Sequence rounds by checking only one continuation fits, Reckoning targets by searching every combination of the numbers, and Cadence phrases by confirming they still fit the keyboard once moved. A level that failed its check would fail the build.

Deduction offers hints. The others do not — but Circuits gives you a slightly larger instruction budget than the shortest possible route, and Reckoning lets you undo any step.

Why is a level locked?

Levels unlock in order, with one always open ahead of the furthest you have solved, so a level you cannot crack never becomes a hard wall.

Can I turn the sound off?

Settings → Sound. The tones are generated by the browser rather than loaded as files, so turning them off saves nothing but your patience.

I find the animation uncomfortable.

Cortex honours your device's "reduce motion" setting automatically — the robot moves instantly, and the shake on a wrong answer becomes a static outline instead.

Is it free? Are there ads?

Free, no ads, no purchases, and no tracking beyond the optional anonymous measurement you are asked about once and can change at any time in Settings.

Which languages?

Ten: English, Spanish, Catalan, German, French, Portuguese, Swedish, Norwegian Bokmål, Danish and Chinese. Cortex follows your browser's preference and you can override it in Settings. Only the language you are using is downloaded, not all ten.

The legal pages exist in all ten as well, but the Spanish versions are the binding ones.

Cannot find your language? Your browser can translate this page — look for “Translate” in its menu. The translation is done by your browser, not by this site.