Nandgarden

About Nandgarden

You are given one part: a NAND gate. Its output is low only when both of its
inputs are high. Everything else in this game — inverters, multiplexers,
adders, memory, an arithmetic logic unit, a working processor — is something
you build out of it.

Nandgarden is a 143-puzzle engineering campaign across eight chapters. Drag
parts onto a grid, route wires with a finger, and watch signals propagate at
real gate delay. Tap any input pin and the board goes live: the wires light up,
the outputs settle, and you can see a design working before you ever press
Verify.

THE LADDER, ON A PHONE

Chapter one gives you nothing but NAND, and you derive NOT, AND, OR, XOR and
the rest from it. Chapter two is routing — multiplexers, decoders, encoders,
buses. Chapter three is arithmetic, from a half adder to a three-bit
multiplier. Chapter four teaches a circuit to remember, starting with two
cross-coupled gates and ending with a register file. Chapter five assembles an
arithmetic logic unit. Chapter six builds the machine around it. Chapter seven
is twenty-four assembly programming puzzles on the processor you just designed.
Chapter eight takes every unlocked part away again and asks you to rebuild the
classics from raw NAND, under a gate budget.

YOUR PARTS CARRY YOUR NUMBERS

When you solve XOR, XOR becomes a placeable block — priced at whatever your
solution actually cost. Build a wasteful adder and every later circuit that
uses one inherits the waste. By the assembly chapter, your machine's cycle
count is derived from the settling time of the arithmetic logic unit you
personally built. Two people can write identical programs and finish in
different numbers of cycles.

THREE SCORES, NOT ONE

Every correct circuit is measured three ways, independently: gate count,
propagation delay along the critical path, and board area. They genuinely
conflict — balanced trees cut delay and cost area, shared terms cut gates and
lengthen paths — so there is no single number that captures a good design and
this game does not invent one. Each score is placed on a histogram against par,
and par comes from a reference design that the build verified against the same
specification your circuit is checked against.

WHEN IT FAILS, IT TELLS YOU WHY

Verification runs the complete truth table where it is small enough and a
curated set of edge cases and deterministic vectors where it is not. A failing
run names the exact input combination that broke, loads it onto your bench, and
shows what each output should have been. A scope panel draws the waveforms with
the mismatched steps highlighted. Oscillating circuits are reported rather than
left to spin.

AN ILLUSTRATED MANUAL

One hundred and fourteen pages, bundled and readable offline: a datasheet for
every part with its pinout, truth table, timing waveform and application notes;
twenty-six theory pages covering Boolean algebra, De Morgan's laws, Karnaugh
maps, fan-out, critical paths, hazards, setup and hold, metastability, two's
complement, carry lookahead and instruction-set design; plus reference tables,
a gate symbol chart, the full instruction set and a glossary.

ALSO INCLUDED

A free sandbox bench with eight inputs and eight outputs and no specification
at all, saved locally. A purist mode built into the final chapter. Reference
designs you can inspect after solving. Netlist sharing through the system share
sheet.

WHAT IT DOES NOT DO

Nandgarden is a one-time purchase. There is no advertising, no in-app purchase,
no subscription, no account and no telemetry. It makes no network connections
of any kind and works identically on a plane. Your progress, saved benches and
personal bests are stored on your device and go nowhere else.

Everything in the bundle — the artwork, the sound, the music, the manual and
all 143 puzzle specifications — was generated by the project's own pipeline. No
third-party assets are included.