INCREMENTAL × POSTAL PRODUCTION LINE

Return to Sender

Run the post, from a village counter to an international network, one postcode at a time.

⏱ ABOUT 3 HOURS · RUNS IN YOUR BROWSER · SAVES AUTOMATICALLY

ADDED: 10 OCTOBER 2026
LAST UPDATED: 10 OCTOBER 2026
MODEL: CLAUDE OPUS 5.5
REF: 760e0871

We asked for “interesting elements”. The machine gave us ticking parcels, chain letters, a stamp album and a postmistress who vanished in 1952. Nobody asked about the postmistress. Nobody dares.

THE ENTIRE GAME DESIGN DOCUMENT

THE PROMPT THAT STARTED IT ALL 🧠

> Create a visual incremental game based around mail and a sorting office - add some interesting elements to switch it up from your run of the mill incremental games.▌

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

Return to Sender is an incremental game about running the post, from the counter of Little Wickham Post Office to an international network. The map shows your sorting hubs, the roads between them and the posties and vans on their rounds. Go into a hub and you get a cutaway of its sorting floor: mailbags drop down a chute, the post rides a belt past your staff to your desk, and you read each postcode and sort it by hand.

Every hub is a production line, not a single number. Post in, the belt, sorting, dispatch and delivery each have a rate, and the slowest holds up the rest. Bigger hubs add parcel and freight lines with roll cages and forklifts. Every item is first or second class with a deadline: late post is refunded, damaged parcels cost compensation, and mis-sorted post comes back late.

Chain letters, ticking parcels, homing pigeons, a dead letter sack, a stamp album, postal reform for permanent postmarks, and letters from Agnes Penhallow, the postmistress who vanished in 1952. Drawn on a Canvas 2D with synthesised music and no runtime dependencies. Royal Mail was not consulted. Neither was a human.

🎮 CONTROLS

1–9 or click to sort
0 recycles junk mail
Space opens a ticking parcel
R rings for the collection
M or Escape for the map, Tab to switch lines

✨ GAME-CHANGING FEATURES

Five hubs, from a village post office to the International Mail Gateway
A visible production line: post backs up wherever your bottleneck is
Letter, parcel and freight lines, each with its own staff and machines
First and second class deadlines, refunds and hub reputation
Ticking parcels, chain letters, homing pigeons and a dead letter sack
Postal reform for permanent postmarks, and a story with an ending

How To Play

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

Start in Little Wickham Post Office. Read the postcode of the item at your desk and sort it with the number keys or by clicking its pigeonhole.
Hire staff and buy upgrades to speed up each stage: post in, the belt, sorting, dispatch and delivery. Each upgrade card says whether it helps your bottleneck.
Ring for the collection when the loading docks fill, sign for recorded deliveries and pigeons, and open ticking parcels before they go off.
Open new hubs from the map. Each keeps working while you’re elsewhere and passes post on to the next, deadlines and all.
Hit Head Office’s monthly targets for bonuses, and open the dead letter sack for money, stamps and something stranger.
From Greater Mardle on, hand the network back in a postal reform for postmarks that add 25% to every delivery, for good.