Balance faucets against drains — the flow, not the total, defines the economy
GDC-L1-ECON-000101
Statement
A game economy is defined by its faucets (sources that create resources) and its drains (sinks that destroy them). Its health is a matter of flow: sinks must remove resources at a rate matched to what faucets generate. Watch the rates, not the stockpiles.
02
Rationale
Resources in a game are created from nothing at faucets (quest rewards, loot, minigames) and, ideally, destroyed at sinks (repair costs, consumables, fees) [S-economy-design]. What determines whether the economy stays healthy is the balance of flows — if faucets pour in faster than sinks drain out, resources accumulate, purchasing power falls, and the currency inflates toward worthlessness (ECON-0004); if sinks over-drain, players feel starved. This is the economy-specific deepening of SYS-0008 (model resources as an internal economy): SYS-0008 says treat resources as sources/sinks/converters; this says the tuning target is the flow rate through them, and it interacts directly with feedback loops (SYS-0004 — a faucet that scales with wealth is a positive loop that accelerates inflation). Designers who watch only the current totals miss the trend that will break the economy weeks later.
03
Applies when
Any game with accumulating resources — RPGs, MMOs, survival, city-builders, strategy, economy sims, and most progression systems. The larger and longer-lived the resource pools, the more flow balance dominates.
04
Does not apply / Exceptions
Games with tiny or no persistent economies (most arcade, action, puzzle) don't need flow modeling. Deliberately inflationary designs exist (idle/incremental games are about numbers exploding — there the "economy" is the spectacle of growth, and control comes from scaling costs alongside, not from stable purchasing power). Short, closed-loop economies (one playthrough, no persistence) tolerate looser balance.
05
Implementation
Enumerate every faucet and drain and estimate its rate; model the net flow over time (economy -simulation tools help) rather than eyeballing current balances. Watch for faucets that scale with player wealth, count, or game age — those are inflation engines (ECON-0004). Tune by adjusting rates, and prefer adding/strengthening sinks (ECON-0003) over throttling the fun of faucets. Instrument the live economy (telemetry — PLAYTEST-0005) to catch drift early.
06
Disagreement
Little on the flow model itself; debate is about how tightly to control the economy — stable-purchasing-power design (MMO-style, fight inflation hard) vs. deliberately inflationary growth (idle games, where the exploding numbers are the point). The choice follows whether stable value or the spectacle of growth is the goal.
07
Notes
The economy-craft deepening of SYS-0008, and tightly coupled to SYS-0004 (feedback loops are the dynamics of the flow). The parent of the more specific ECON principles (sinks, inflation, currencies). Confidence 4.
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Connected principles
S