2.5D STATION PUZZLE × SPEEDRUN

Eki Stamp Rally

Find the station stamp, stamp your book, catch the right train. Twelve stations, from Mitake to Shinjuku.

⏱ TWELVE STATIONS AGAINST THE CLOCK · RUNS IN YOUR BROWSER · SAVES AUTOMATICALLY

ADDED: 10 OCTOBER 2026
LAST UPDATED: 10 OCTOBER 2026
MODEL: CLAUDE OPUS 5.5
REF: d6df70c7

Asked for ten levels. Delivered twelve. Every departure melody synthesised by a machine that has never missed a train, because it has never been on one. Shinjuku is exactly as confusing as the real thing.

THE ENTIRE GAME DESIGN DOCUMENT

THE PROMPT THAT STARTED IT ALL 🧠

> Create a puzzle game based on finding Eki stamps in Japanese train stations. I'm imagining a 2.5D game, where there are steps up and down from each floor (or level, each "level" doesn't necessarily need to be an entire floor, it could be an underpass for instance.) For each station, you arrive on a train, you need to find the eki stamp (which will be outside one of the exits of the station), you stamp your eki stamp book, with a nice animation, and then you need to them get back to the train on the correct platform to get to the next station on your list. 10 levels. The first station should just be two platforms, an underpass or overpass, and a gate line on each platform. The 10th level should be Shibuya or Shinjuku levels of confusing. Note the special train jingles/station jingles they have, they are an important part of the sound scape! There should be increasing number of other passengers which block you (and aren't affected themselves by you running in to them. The passengers walk, but you can run. Being Japanese, the passengers are organised, they don't walk randomly, but the stations are chaotic. The game should be speed run friendly (with a typical speed run panel?) How you identify the correct platform to head to next is your call.▌

That’s it. That’s the brief. Everything else — every line of code, every pixel, every note — came out of the machine. Typos preserved for authenticity.Disclosure: a human may have intervened afterwards, when the machine made the first upgrade cost more than the GDP of Wales, or decided a run should last eleven hours. Even then, the human only fixed it by typing more prompts and sighing loudly. 🫠

About the Slop

Eki Stamp Rally is a 2.5D puzzle and speedrun game set in Japanese railway stations. You travel from Mitake, in the mountains, to Shinjuku in twelve stations. At each one you get off the train, find the eki stamp outside one of the exits, stamp your book and board the right train to the next station.

Each station is bigger than the last. Mitake has two platforms and an underpass. Shinjuku has eight island platforms, the Odakyu terminal, an underground floor, a south concourse and seven rows of gates. The objectives tell you the exit and your next train’s line and destination, but not the platform: read the departure boards and signs, or listen for the announcement. Passengers keep left, queue at the doors and do not move for you.

A split timer tracks every station against your personal best, with gold segments and a fixed random seed so every attempt is the same. Each station has its own departure melody, plus the door chimes, the gate beeps and the birdsong at the stairs, all made in the browser. Not one human pressed a station stamp in the making of this game.

🎮 CONTROLS

WASD or arrows to run
Shift to walk
Q and E to zoom
Space skips the arriving train
R resets, Esc pauses

✨ GAME-CHANGING FEATURES

Twelve stations, from two-platform Mitake to full Shinjuku
Multi-floor stations with stairs, underpasses and concourses
Find your platform from departure boards, signs and announcements
Orderly crowds that queue, keep left and never get out of your way
A speedrun split timer with personal bests, gold splits and station practice
A departure melody for every station, synthesised in your browser

How To Play

A quick guide for your first session. The machine wrote the game; we wrote this bit from its README.

Get off the train and check the objectives: the exit with the stamp, and the line and destination of your next train.
Run through the station to that exit. Stairs join the floors, and the camera cuts away the floors above you.
Stamp your book at the stamp stand outside the exit.
Find the platform for your next train on the departure boards above the gates and on the platform signs, or listen for the announcement.
Get back through the gates and on to the train before it leaves. Passengers won’t move for you, and bumping into them slows you down.
Beat your splits. Station select lets you practise any station you’ve collected the stamp for.