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2-player playthrough · New Discoveries

Underwater Cities: glossary and rules terms

Definitions from the authored tutorial, with stable links for sharing a particular term. The selected edition and scenario determine how each rule applies.

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27 terms

Matching colors

A card always accompanies an action tile. A matching card may resolve its effect; a mismatched card is discarded without its effect. Resolve the complete card effect before or after the complete slot.

Rule reference: pp.7–9

Action slot

A shared space occupied by one action tile for the round. In two-player play use the 1–2-player side. The always-available fallback gives two credits and two cards.

Rule reference: pp.7,20

Action card

A claimed card marked A may be used only through an appropriate effect, normally once per era. The assistant counts toward the maximum four. Before claiming a fifth, discard an old one; an unused old action may be used immediately.

Rule reference: pp.8,12,16

Special card

Take an available Special into your hand using the appropriate slot. Acquisition is free; pay the printed credits when playing it with a matching color. Museum can instead claim one directly for free.

Rule reference: pp.9,14; expansion pp.6–7

Hand limit

Before your turn keep only three cards. Draw one at the end of each turn. Cards are private; selecting a tutorial perspective reveals only that player’s hand.

Rule reference: pp.7,14,16

Era

The game has three eras. Productions follow rounds 4,7,10. At the first two era changes, replace the old draw/discard piles and draw three cards per player; old cards held in hand may be retained.

Rule reference: pp.15–17

Quick Start

New Discoveries replaces round 1 with resource-tile and assistant choices. Select resource tiles in reverse player order. Do not also take the base starting resources.

Rule reference: pp.4–5

Museum

In Museum play, reveal a discovery after construction at its marked site, resolve its immediate tile benefit, then place it in the group corresponding to your discovery count. Rewards after group I are exclusive.

Rule reference: pp.6–7

Discovery

Museum boards have five covered sites. Building there reveals the fixed hidden tile. Its benefit resolves before the Museum placement. A hidden front is not known in advance.

Rule reference: pp.6–7

Connected

A city belongs to your network when tunnels connect it to the starting city. Buildings produce only beside connected cities; a tunnel must be adjacent to at least one connected city to produce.

Rule reference: pp.10–11,15

City

Place a city at an empty printed city site adjacent to an existing city along a printed tunnel position. Ordinary construction costs two steelplast, one kelp and one credit. A connecting tunnel need not already exist.

Rule reference: pp.10–11

Symbiotic city

Usual cost: one steelplast, one kelp, one biomatter and two credits. A connected symbiotic city produces two points. A card’s specified replacement cost can differ.

Rule reference: pp.10–11,15

Farm

Costs one kelp. A connected farm produces one kelp; upgraded adds one point. Two upgraded farms at one city add one more kelp and point beyond their individual output.

Rule reference: pp.10,15

Desalination plant

Costs one credit. Connected production is one credit, with one biomatter added when upgraded. Two upgraded plants at one city add one extra credit, not another biomatter.

Rule reference: pp.10,15

Laboratory

Costs one steelplast. Connected production is one science, plus one steelplast if upgraded. Two upgraded laboratories at the same city add one extra steelplast.

Rule reference: pp.10,15

Tunnel

Usual cost is one steelplast and one credit. Extend the connected tunnel network along printed sites; empty city sites may be crossed. Normal productive tunnels yield one credit; upgraded ones add a point.

Rule reference: pp.11,15

Upgrade

Usually pay one science to stack a second matching building token or flip a tunnel. Cities cannot be upgraded this way. A structure cannot be upgraded a second time. Card-specific costs override usual ones.

Rule reference: pp.12,15

Biomatter

In construction, biomatter may replace steelplast or kelp. It does not replace unrelated card payments. Feed with kelp first, then biomatter; at final scoring each remaining biomatter sells for two credits.

Rule reference: pp.11,17

Federation track

Advance through printed bonuses; the higher marker acts first next round. At a tie the newest marker is on top. Unmoved players keep their relative order. Reset after determining the order.

Rule reference: pp.12,15

Production

After rounds 4,7,10, resolve connected cities, buildings, productive tunnels, metropolises and production cards. Count individual output and upgraded-pair bonuses separately.

Rule reference: pp.15–16

Feeding

After production feed each connected city with one kelp, then biomatter for any shortfall. Lose three points for each still unfed city, stopping at zero. Final feeding precedes resource-scoring cards.

Rule reference: p.17

Expansion site

Each city has three ordinary building sites and a fourth expansion site. The fourth requires a permitting card or assistant, such as Manager. Normal costs still apply unless specified otherwise.

Rule reference: p.10; assistant face

Blue metropolis

Connecting a blue tile grants its immediate benefits and any production effect during remaining productions. It is not a city and needs no food.

Rule reference: pp.14,20

Brown metropolis

This board connection requires both printed tunnels. Brown tiles score only at game end; exact formulas depend on the actual assigned tile.

Rule reference: pp.14,17,20

Green metropolis

Museum B can award a green tile. Place it beside the starting city, immediately connected without a tunnel, then apply its printed effect.

Rule reference: pp.6–8

Building diversity

At final scoring, connected cities score by distinct building types: none 2, one 3, two 4, three 6. Extra copies and upgrades do not increase this type count.

Rule reference: p.17; relevant card faces

Final scoring

After final production and feeding, score brown metropolises, scoring cards, connected cities, then leftovers. Sell biomatter for two credits each; any combined four credits/kelp/steelplast/science score one point. Final player order breaks ties.

Rule reference: p.17

Sources and scope

The source tutorial checked publisher rules and component references on 11 September 2026. This authored route uses two players, Quick Start and Museum B; other player counts, the ordinary round-one opening and alternative expansion modes are outside its scope.

Reading guide reviewed 2026-09-15; based on tutorial v1.0.3. This date records an editorial review of the existing tutorial, not a new rules edition. Strategic suggestions are conditional interpretations, separate from official rules.