Underwater Cities rules: how to play and how to score

Underwater Cities quick rules

The goal

You build cities under the sea, connect them with tunnels and surround them with buildings. The game lasts ten rounds, split into three eras. You score points during the game, mostly in the three Production phases, then at final scoring: the most points wins.

A turn

Each round, everyone takes three turns in the order of the play-order track. On your turn, you place an action tile on an available action slot and play a card from your hand. If the card matches the slot’s color, you perform the action and the card’s effect, in either order; otherwise, only the action. Then you draw a card.

Colors and slots

Green cards are the strongest but green slots the weakest; yellow is the reverse, and red sits in between. The always-available slot gives 2 cards and 2 credits to anyone, with no card effect. With 4 players, the action-cloning tile lets one player per round take an occupied slot for 1 credit.

Cards

A card with an instant effect resolves, then is discarded. Other cards are claimed and placed near your player board: permanent effects, action cards (once per era, four at most with your Personal Assistant), production cards and end-scoring cards. Special cards are taken with a dedicated slot, and you pay credits for their effect.

Building

A white city costs 2 steelplast, 1 kelp and 1 credit; a purple symbiotic city 1 steelplast, 1 kelp, 1 biomatter and 2 credits, and it produces 2 points every Production. A farm costs 1 kelp, a desalination plant 1 credit, a laboratory 1 steelplast, a tunnel 1 steelplast and 1 credit. Biomatter can replace kelp or steelplast.

Your network

A city is connected when a tunnel links it to your starting city, a building when it is next to a connected city. Anything not connected produces nothing and scores nothing at the end. Building on a site that shows a resource gives it to you right away, and a metropolis only gives its benefits once its tunnels connect it.

Upgrading

Tunnels and buildings are structures. Upgrading one usually costs 1 science: you stack a second token or flip the tunnel over. An upgraded structure produces more, and can only be upgraded once.

The Federation track

Some slots and cards let you advance on the Federation track, with the bonus of each space. On an occupied space, your marker goes on top. At the end of the round, the player farthest ahead will go first, then the markers return below space 4. On space 1, each advance scores a point.

Production

After rounds 4, 7 and 10, each connected farm produces 1 kelp, each desalination plant 1 credit, each laboratory 1 science, each tunnel next to a city 1 credit; upgraded, the farm and the tunnel also give a point, the plant a biomatter and the laboratory a steelplast. Then each connected city eats 1 kelp, or else 1 biomatter, or else 3 points.

End of the game

After the third Production, final scoring follows: brown metropolis, end-scoring cards, connected cities and leftover resources. In a tie, the player who would play first according to the Federation track wins.

Beginner traps

You play in play-order track order, not clockwise. A city without a tunnel does not count, even surrounded by buildings. A tunnel only produces next to a city. And keep kelp for every Production.

Solo game

Three neutral action tiles block one slot of each color and move every round; a fourth blocks a random slot if you did not advance on the Federation track. You win with at least 7 connected cities and 100 points, 125 with New Discoveries.

How to score Underwater Cities

Points scored during the game

Your space on the scoring track before final scoring: Production, cards and the Federation track are already included.

Brown metropolis

Only if both of its tunnels are built. Depending on your tile: 3 points per connected metropolis; 5, 7 or 9 points for 8, 9 or 10 tunnels connected to cities; 4 points per set of 4 different upgraded structures; 2 points per Special card paid for; 4, 8 or 12 points for 5, 6 or 7 connected cities.

End-scoring cards

The points from your end-scoring cards, including resources they convert into points.

Connected cities

For each city connected to your network: 2 points with no buildings, 3 with one type of building, 4 with two types, 6 with a farm, a desalination plant and a laboratory.

Leftover resources

Each biomatter is worth 2 credits; then 1 point for every 4 credits, kelp, science or steelplast, in any combination.

Ties

The player who would play first in the order set by the Federation track at the end of the final round wins.

New Discoveries

With the New Discoveries expansion, a doubled metropolis or the Museum can double the brown metropolis points.

Data Era

With the Data Era expansion, a city is worth 5 points with three building types and 8 with all four, data center included; each leftover data disc counts as one credit.

Worked example

Emma has 92 points on the track. Her brown metropolis scores tunnels connected to cities: she has 9, so 7 points. Her end-scoring cards give 11 points. Her connected cities: two with all three types (6 + 6), one with two types (4), one with one type (3) and one with no buildings (2), so 21. She has 13 credits, 2 kelp, 1 science, 1 steelplast and 2 biomatter left: 13 + 2 + 1 + 1 + 4 = 21 credits, so 5 points. Total: 92 + 7 + 11 + 21 + 5 = 136 points.

Common mistakes

• Scoring the brown metropolis when one of its two tunnels is missing: it gives nothing.
• Scoring a city that no tunnel connects, even surrounded by buildings.
• Counting tunnels as a building type for cities: only farms, desalination plants and laboratories count.
• Keeping resources instead of spending them on an end-scoring card: 4 resources are only worth one point.

How to set up Underwater Cities

Setup is done in four phases. The player count changes the board side, the purple domes and the starting resources; the solo game has its own phase at the end.