The same week for everyone: Slack, Jira, GitHub and VS Code in one Chrome tab, a Next.js codebase with hidden CI tests, and AI teammates. Use it before day one, as an interview, or as training.
Each use runs on the public Sim today. What's still in early access is the layer for you: team views, results and custom codebases.
Send new hires the Sim before their start date. They arrive knowing how tickets, CI and review fit together, so week one goes to your code instead.
Replace a puzzle round with a work sample: a customer bug, an unfamiliar codebase, CI and a reviewer. You see how someone works, not what they memorized.
Give juniors, interns and apprentices a safe place to repeat the loop: read the ticket, reproduce, fix, push, read red CI, take review.
Most coding interviews test puzzles. The job is reading someone else's code, asking good questions and getting a red build to green. This plan uses Wednesday's ticket, SEAT-12, played live while the candidate shares their screen.
The candidate opens the Sim in Chrome, already past Tuesday, and picks Expert mode in the Career menu.
They read SEAT-12 and reproduce the bug in the Seatly tab. Ask what they expect the fix to touch.
They find the rule, run the tests and open the pull request. CI is often red on the first push. Watch what they do next.
They read Dev's review and write the note to #support in plain words.
Look at the end-of-day report together: score, CI runs, hints. Ask what they'd do differently.
| What you watch | Where it shows up |
|---|---|
| Reads the ticket before the code | Jira, and the "Read the ticket" achievement |
| Reproduces before fixing | The booking they make in the Seatly tab |
| Asks good questions | Their Slack messages to Maya, Sam and Dev |
| Handles a red build | The failing checks on the PR, and their next change |
| Explains to a non-engineer | The note to #support, checked against a rubric |
| How much help they needed | Hints and red builds on the end-of-day report |
Every screen below is from one real playthrough of SEAT-12, a customer bug. Scroll sideways through the whole loop: ask, read, find, push, fail, fix, get reviewed, merge.
You DM Dev, the senior engineer. He points you at canSeat() in lib/booking.ts. His reply is written live, in character.
Steps to reproduce and acceptance criteria. While you read, Sam from support pings: the restaurant called again.
party <= seats + 2, because "restaurants can add chairs." npm test passes, 22 of 22. None of them test this.
Hidden tests run as CI. Three fail, so merging is blocked until the checks pass.
"rejects a party of 6 at a 4-seat table": expected true to be false. The check names tell you what is still wrong.
Drop the + 2 and the comment that justified it. Open the pull request again.
All four checks pass. Dev reviews the diff and leaves comments. Then you merge, and the ticket moves to Done.
Score 100, grade S: no hints and no extra red builds. 660 XP and the achievements you earned.
Unedited captures of the Sim in Chrome, 1 October 2026. Teammate replies and code review are written by AI each time, so yours will read differently.
| Feature | Sim work sample | Algorithm puzzle | Take-home project | Pairing on your code |
|---|---|---|---|---|
| Looks like the real job | - | partly | ||
| Same task for every candidate | - | |||
| Nothing for the candidate to set up | - | - | ||
| Tests check the fix automatically | - | - | ||
| Keeps your own code private | - | |||
| Shows how they ask for help | - | - | ||
| Fits in an hour | - |
Puzzles test something real. They just test less of the job.
A shorter road to a new hire's first merged PR, and a fairer interview round.
One realistic task for every candidate, with clear things to watch.
A hands-on first week that is the same for every hire.
A safe place to practice the loop before touching production.
A realistic rehearsal of a new engineer's first week: a real codebase, tickets, CI and review from simulated teammates, in the browser.
Yes, as a live work-sample round over screen share, using the plan on this page. There's no proctoring, interviewer dashboard or results link yet, and teammates help if asked, so it's built for a conversation with a candidate, not an unsupervised test.
It tests different things: reading unfamiliar code, reproducing a bug, reading red CI, taking review and explaining a change. Many teams will want it alongside other rounds, not instead of all of them.
The five-day first week in Next.js and TypeScript, graded each day, free to play. A team view of results is in early access, and more stacks are built with early-access teams.
No. They open the Sim in Chrome or Edge and start. Progress saves in their browser.
Next.js, TypeScript, Node and Vitest, with hidden tests as CI. Custom stacks are on the roadmap.
A flat monthly price per team, no per-seat fees. Confirmed before you commit.
Arclab
