Resource Loops — Gather → Convert → Spend

What it is. The cycle at the heart of production games: gather a raw resource, convert it into something more useful, spend the result on progress — which unlocks better gathering, and the loop turns again, wider. The design work is deciding where the loop narrows — the bottleneck the player must solve.

Player fantasy / why it’s fun. “I built the pipeline that makes the thing that makes me stronger.” Each loop closed is a small system mastered. The pull is the next bottleneck — the one resource you don’t have enough of yet.

When to use / when NOT

Use it when	Skip it when
Progress runs through making, not just buying	The game has no crafting/production layer
You want pacing to emerge from bottlenecks, not timers	A flat currency (`system-economy`) already carries it
Chains of resources create planning/optimization depth	Extra steps would be busywork with no decision

A resource loop is system-economy with structure: instead of one bucket, a directed chain where each node’s output feeds the next. Use it when the shape of the chain — what feeds what — is itself a puzzle.

Variants

Variant	Shape	Depth from	Example
Linear chain	A → B → C → goal	Clear ramp; one bottleneck at a time	Stardew crops → artisan goods → cash
Branching tree	One input, many outputs	Prioritisation	Factorio iron → plates/gears/etc
Converging web	Many inputs, one output	Logistics puzzle	Factorio science packs
Cyclic (renewable)	Output feeds back to input	Sustainable scaling	Seeds from crops; power → mining → power
Sink loop	Convert → spend → gone	Pacing pressure	Fuel: gather → burn → gather (survival)

Tuning levers

Lever	What it controls	Healthy range / rule
Bottleneck placement	Where the player feels scarcity	One clear binding constraint at a time — that’s the current puzzle
Conversion ratio	Inputs per output	Legible (2:1, 5:1), not 7.3:1 mystery math
Chain length	Steps from raw to result	Long enough to plan, short enough to hold in head; add steps as content, not on day one
Throughput vs storage	Flow rate vs stockpile	Flow-limited = active play; storage-limited = idle waiting
Renewability	Whether a resource runs out	Renewable = sustainable; finite = a clock (`system-economy` inflation)
Parallel loops	How many run at once	More loops = more to juggle; ramp the count

The bottleneck is the pacing. A loop with no binding constraint is a firehose — nothing to optimise. A loop with a permanent bottleneck is a wall. Good design moves the bottleneck: solve iron, now you’re copper-limited, now power-limited. Each move is a fresh puzzle — the same “no deserts, no walls” discipline as an economy’s pacing window ([[FUN.md §14]]).

How it wires to Hayao

The chain is data. Resource counts and converter states live in world.state; each gather/convert/spend is an input action, so the whole production run replays and hashes ([[FUN.md §14]], law 7).
Pacing is provable. Balance-sim the loop with a bot that plays it out, then assert monotone production and no bottleneck desert — the exact incremental verify. The farming truth applies too: surface the player-critical number (“N iron short”) the way farming surfaces “nights left” ([[FUN.md §15]]).
Ratios are law-3 inequalities. “Converter throughput ≥ demand at tier T” is a constraint you state in a comment and assert against the actual config, not a vibe ([[FUN.md law 3]]).
The reinvest-vs-hoard delta is your skill proof: a bot that reinvests output into more capacity beats one that hoards — farming measured 740 vs 236 ([[FUN.md §15]], law 2).

Fails when…

No bottleneck. Everything abundant → no decisions → the loop is a chore of clicking through steps. Always bind one constraint.
A permanent wall. A bottleneck that never resolves halts progress. Move it.
Mystery ratios. Illegible conversion math the player can’t plan around.
Idle throughput. If output accrues while away with no active choice, it’s a timer, not a loop.
Chain too long day one. Ten steps before the first payoff buries the fun. Introduce depth as the player scales, the way src/content/ gates mechanics per act.

Verify

Monotone production, no desert, pacing windows — the balance-sim: [[FUN.md §14]].
Reinvest-vs-hoard skill delta: [[FUN.md §15]], law 2.
Conversion/throughput ratios as asserted inequalities: [[FUN.md law 3]].
Surface the binding number to the player (the farming truth): [[FUN.md §15]].

Composes with

system-economy — a resource loop is an economy with an explicit chain.
system-crafting — recipes are the convert step made combinatorial.
system-tech-tree — research gates unlock new links in the chain.
system-progression — spending the loop’s output is how you grow.
pattern-emergence — interacting loops (power↔mining) generate depth.