KN-86 Development Document

product changes, not each sprint. Shape: Rollings & Morris’s ladder, worn lightly: pitch → world → position → game → platform → documents. Read §1 and §2 to understand the product; read §4 to build against it; everything deeper lives one tier down, linked in place.

Related: README.md (documentation hub) · device/hardware/canonical-spec.md (every hardware value; this document restates none) · software/runtime/orchestration.md (runtime architecture) · software/runtime/economy-model.md (the economy and its simulators) · marketing/narrative/worldbook.md (fiction canon mirror) · adr/ (every decision)

1. The Pitch

Per the book: a vision statement, written without technical constraints. Its job is to expose gaps in the concept and let a reader decide whether the idea deserves a full specification.

A game console where the command line is the controller.
One operator identity that every cartridge reads and writes.
Contracts that span physical cartridge swaps.
A resident commentary channel on its own dedicated display.

The KN-86 Deckline is a handheld terminal that is also a game console. The operator types Lisp. The Lisp grammar is the entire interface: every operation, from checking battery state to completing a contract, is an expression the runtime evaluates. The keyboard’s function block carries the primitives on its keycaps; the REPL sits one keystroke away; the structural editor is a first-class tool.

Software arrives on physical cartridges. Cartridges are capability modules: each adds capabilities to one shared runtime with a self-contained minigame. A cartridge might break ice, trace signals, audit ledgers, or run depth charges. nOSh, the runtime, provides the connective tissue: a mission board that generates contracts, an economy of credits and reputation, and a phase chain that lets one contract require several capabilities. A multi-phase contract means several physical cartridge swaps mid-mission, with deck state preserved across each swap.

CIPHER is the deck’s companion program, in the lineage of ELIZA, PARRY, and doctor.el: a conversational presence rendered as text on its own auxiliary display, a narrow strip above the keyboard. Less a status log than a partner in the situation, it offers observations, hints, and guidance as the work unfolds, closer to KITT than to a syslog.

None of this is simulated. The screen is that display, the keys evaluate Lisp, the cartridges carry the modules. The proposition: a device the operator drives by typing, running jobs on a generated network, with the deck’s own case file growing mission by mission.

The Experience

The operator opens the case and powers on into the HUB, the bare-deck terminal: seven tabs (STATUS, CIPHER, LAMBDA, LINK, SYS, MISSIONS, PROGS), live readouts, CIPHER’s channel, and every first-party program one keypress away on PROGS. It reads as an instrument panel, with the Lisp grammar underneath and the REPL one key away when wanted, no cartridge required (see software/runtime/bare-deck-terminal.md). Insert a cartridge and the deck gains a capability; the mission board starts offering contracts that use it. Complete a contract, collect the payout, watch reputation move. Eject the cartridge and the operator’s identity stays on the deck for the next module.

Sessions are self-paced and offline. The deck does not reach the network on its own, does not update overnight, and raises no notifications. When jostled it shows a faint glitch effect. All state persists on the device.

2. The World

The fiction the operator plays inside, and the reason the mechanics read as a game: you are an operator, a person the legitimate economy no longer recognizes. Government ID is the prerequisite for TradEcon commerce, and operators have lost theirs; deckline contracts are the work that remains.

AetherNet is where that work happens: a stealth mesh with no central server and no registered identifiers, indistinguishable from noise on a spectrum analyzer. Operators describe the mission board as listening: procedural hashes pulled out of the aether and reconstituted locally, seeded by the deck’s own state. On AetherNet an operator is invisible by default. Two things break that. Black ICE, rare defensive software guarding infrastructure that does not want visitors, carries physical consequences for the operator who triggers it. And Edgeware, the software house whose code quietly runs the mission board, sees everyone: a cut of every payout siphons through its shell companies, and operators who climb high enough get noticed, then recruited.

The climb has a destination. A synthetic identity, the economy’s capstone purchase, buys a way back into the legitimate world. CIPHER’s commentary runs on the auxiliary strip through all of it.

The mechanics sit inside this frame: untraceable credits, reputation that lives only on the deck, the offline-first posture, DOSSIER as a case file that keeps growing. Master fiction canon is the Kinoshita World worldbook (local mirror: marketing/narrative/worldbook.md); this section carries only what gameplay depends on.

3. Position

Genre: dedicated-hardware game platform; the software library spans strategy, simulation, puzzle, and roguelike forms unified by a terminal presentation and a shared economy.

Nearest relatives, and where the KN-86 agrees with them:

Relative	What we do the same
Playdate	Dedicated quirky handheld, curated first-party library, hardware personality as product
PICO-8 / Uxn	Tightly constrained fantasy-computer platform; constraints as creative fuel; carts as the unit of software
Zachtronics titles (TIS-100, EXAPUNKS)	Programming-as-play for an audience that wants to think
Roguelikes / MUDs	Text density, glyph vocabulary, depth over spectacle

Where we deliberately differ:

The grammar is the interface. No relative makes the language the only way to drive the device.
Capability model over standalone games. Cartridges extend one persistent world instead of each carrying their own. No shipping handheld does cross-cartridge missions with mid-mission media swaps.
A hardware companion channel. CIPHER has its own physical display and dedicated silicon.
Sound as data. The runtime plays the synthesizer to convey state.

The USP list, held against the book’s five questions (fun? gameplay? why hasn’t it been done? implementable? workable?):

Lisp-native operation. Fun for the target operator (the fluency curve is the game); implementable today (the runtime, REPL, and structural editor run now); workable on 34 keys, because the key layout was designed around the grammar’s actual character set (ADR-0044). The mass-market reflex says “nobody will type parentheses.” The KN-86’s market is the people who will.
Cross-cartridge missions. Create gameplay no single cartridge could (loadout planning, collection value, the swap as ritual); implementable because deck state and save rules already exist (ADR-0011, ADR-0019).
CIPHER on dedicated hardware. The auxiliary display is a cheap part with a large effect; the voice engine and its authoring contract exist (software/runtime/cipher-voice.md).
Informational audio. A proven pattern (software/cartridges/authoring/ascii-design-system.md); the PSG emulator runs today.

This document is the artifact to attack. The concept has survived an external product evaluation (marketing/product-evaluation.md). The remaining standing challenge is execution. The cartridge designs themselves are under revision; see _meta/cartridge-premise-audit-2026-07.md.

Pricing, production-run planning, positioning, and channels live in marketing/pr-faq.md and marketing/marketing-plan.md; this document restates none of those numbers.

4. The Game

How the product works from the operator’s chair. Detail lives in the per-domain specs, linked in place.

The loop

The operator works AetherNet’s corporate hosts, fileservers, and ports (§2). The first-party programs are the investigative tissue and the Lisp grammar drives them; cartridges supply the capabilities and their minigame interfaces.

A session moves through the programs. Mission Control posts the job. DOSSIER holds what the deck already knows about the target. CONDUIT opens a connection to a generated AetherNet address, say a corporate fileserver. Kinoshita Kommander browses what sits on the share. AmberCalc reads the transactions. Once inside a node the work might stay mundane (read the files, copy the ledger, get out), or a gate drops: flagging a suspect transaction loads BLACK LEDGER and its audit minigame; a firewall might present ICE BREAKER’s Pong-like wall the operator has to knock through; a job might mean piloting a drone to an underwater AetherNet port on DEPTHCHARGE’s sonar display. Mundane access and minigame gates mix within one mission, and which one the operator hits next is part of the tension.

Each mission plays as a small mystery: assemble the evidence, deliver the success conditions, collect the payout. Resolution locks new facts into DOSSIER, and the deck’s story reads like interactive fiction with instruments, accumulating in DOSSIER and Universal Deck State from mission to mission.

On the board, the choice is real: a quick single-phase job, a longer chain, or work picked because it pulls in the cartridge the operator feels like playing. A job is eligible when the operator owns the cartridge carrying its required capability, and board filters include or exclude capabilities at will. Around the contracts, free play: the REPL for errands and experiments, programs used directly, cartridges’ own modes outside contract work. The intended texture is deliberate, legible, and operator-paced: mastery shows as economy of keystrokes. (Runtime detail: software/runtime/orchestration.md.)

The economy

Progressive disclosure. The operator starts with a limited kit: each cart ships a minimal working verb set, and a subset of the first-party programs is active from boot. The board occasionally offers a mission that is nearly impossible without a capability the operator lacks, with a fair long way around, so the mission is a lesson rather than a wall; on debrief the missing verb, program, or equipment appears in the shop with a price. The struggle is the advertisement, and buying converts a felt gap into capability.

Credits are the only spendable element: contracts pay them, and they buy verbs, equipment, program tiers, rig upgrades, and consumables. Reputation is standing, never spendable: it gates which offers appear, and failure costs it (failing late costs more than abandoning early). DOSSIER facts are investigation output, never bought or spent. Everything acquirable arrives through one of three channels: bought, discovered (CONS composites the shop never sells), or granted (the starter kit). The journey stays generous and legible at first (the operator ends session one having bought something), opens into save-or-churn choices mid-game, and ends in work a newcomer cannot reach: top offers gated by reputation, jobs gated by a veteran’s DOSSIER, and one capstone purchase, the synthetic identity of §2. The model, knobs, and numbers live in software/runtime/economy-model.md and its career simulators.

The cartridges

Cartridges are the levels: they shape core gameplay and carry design weight. The launch library is four capability cartridges, each with its own design bible (software/cartridges/modules/): ICE BREAKER (network intrusion, the pack-in and every operator’s first session), NEONGRID (city traversal and operator onboarding), DEPTHCHARGE (maritime reconnaissance), and BLACK LEDGER (forensic accounting). The library grows toward the full 17-cart plan across the capability taxonomy.

Missions are not hand-authored levels: templates parameterized by world state generate them, so the board never repeats and difficulty tracks reputation. A worked contract: an ICE BREAKER sabotage of a financial target triggers a BLACK LEDGER audit phase. The operator breaches the network under a converging-ICE timer with CIPHER commentary, swaps to BLACK LEDGER when the board flags the handoff, traces the shell-company topology at BLACK LEDGER’s slower, patient tempo, then debriefs with a reputation gain and a new fact in the dossier.

The deck differs from the console a designer might assume: no session wall exists. Deck state persists, and world continuity runs through DOSSIER: generation reads the case file, so a corp or a person from an earlier mission can resurface with their story furthered. Cartridge design treats the world as shared and ongoing rather than a fresh level instance (authoring rules: software/cartridges/authoring/).

CIPHER

The companion program of §1, on its own display. In play it earns its keep as an informant: observations about the node you are in, hints when a trace stalls, guidance at decision points, references to what the deck’s case file already holds. Engine and authoring contract: software/runtime/cipher-voice.md (ADR-0015).

Interface

A split 34-key board. The left half carries the Lisp function block, the primitives printed on the keycaps. The right half carries digits (with multi-tap text entry) and punctuation; a shift layer completes the grammar’s full character set in at most one held key. Two trackpoints drive one pointer. TERM is context-sensitive: by default it summons the REPL; in specific surfaces it captures seeds or serves the surface’s contextual action. nEmacs, the structural editor, is the heavy tool for editing expressions and authoring on-device. Key layout: ADR-0031/0032/0044; dispatch model: software/runtime/input-dispatch.md; REPL: software/runtime/repl.md.

Look and sound

Amber phosphor glyphs on black, on both displays. One 8×8 glyph vocabulary renders at mixed integer scales, so a screen composes dense body text with poster-sized numerals. Motion stays restrained: two sanctioned animation styles, an ambient glitch system driven by the accelerometer, and idle attract behavior. The CIPHER-LINE strip glows in its own yellow. The three-voice PSG stays terse and informational, turning melodic to mark a completion or reward. Values and geometry: device/hardware/canonical-spec.md; animation: software/cartridges/authoring/animation.md.

Link play

Two decks can link locally for asymmetric play: one operator runs a capability while the other opposes it, sharpest as an ICE BREAKER intrusion against a Sysop defender. Discovery stays proximity-only, with no internet multiplayer, by design. The rest of the social surface is physical: operators lend cartridges, share seeds, and pass the deck hand to hand.

Platform constraints cartridge authors design against

Cartridges draw only the content region; the runtime owns the two frame rows (ADR-0027, screen-design rules)
CIPHER renders only on the auxiliary display; one designed exception (ADR-0015)
Per-cartridge saves live on the cartridge; contract state survives swaps (ADR-0019)
The deck is offline-first; on power-on the world advances by the real elapsed time (ADR-0045)
Cartridge code cannot reach system-tier surfaces; the capability boundary is enforced by the runtime

5. The Platform

Hardware is fixed by the Canonical Hardware Specification (device/hardware/canonical-spec.md): a single-board computer with a realtime coprocessor, primary IPS display plus auxiliary OLED, split keyboard, PSG audio through a codec, battery subsystem, and hardcase. This document repeats none of those values.

The software stack is the kn-86 monorepo: runtime/ (libnosh, the SDL-free runtime), hosts/device/ (the device target), hosts/emulator/ (a desktop build used during development), ui/, sdk/, and carts/, with the KEC Lisp language as the single fetched dependency.

6. The Documents

This document is the top of the ladder. Below it:

Layer	Where
Product-level design	this document, §4
Per-cartridge design bibles	`software/cartridges/modules/`
Authoring contracts (screens, animation, maps, economy hooks)	`software/cartridges/authoring/`
Runtime specs (board, CIPHER, HUB, REPL, input, economy model)	`software/runtime/`
API reference (NoshAPI, grammars, versioning)	`software/api-reference/`
Decisions and their reasoning	`adr/`

The map from any question to its owning document is README.md. When code and a document disagree, the working code wins and the document gets fixed in the same change. The product is ready when the code and §4 describe the same machine.