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21Moon

Designer: Jonas Jones, Scott Petersen

Lunar mining in the year 2117, with temporary permits and an end-of-game fixed by the calendar.

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21Moon Contents

How it works

Setup
  • ₡600 (2 players), ₡540 (3), ₡410 (4) or ₡340 (5); ₡12,000 bank
  • Minerals are scattered at random over the red hexes
  • Each company already has a station at its [LB] and another at the [SP]
  • One of the 7 companies is held back until stock round 3
  • Initial auction of 6 privates, as in 1830
Stock round ×1
  • Sell, then buy
  • Start a company: par price 60, 70, 80 or 90
  • Incremental capitalisation: each [IPO] share pays the treasury
  • The president can swap one of their shares for one the company holds
Corporate round ×1
  • Each company can issue shares to the market (and collect for them)
  • …or buy shares of other companies
  • That way a company can reach 50% and float
Operating round ×2 (×3 in the last)
  • Private income
  • Each company, highest share price first:
  • 1. Two tiles, one from each base (hill ₡10, mineral ₡20, mountain ₡40)
  • 2. One station
  • 3. Run transports (2 per base; one can be moved between bases)
  • 4. [LB]: withheld. [SP]: paid out
  • 5. Buy transports (must own some)
↻ Repeats until the end
End
  • Fixed schedule: ends with operating round 5.3 (11 in total)
  • Or if all players but one go bankrupt
  • Each east-west bonus token adds ₡50 per 10% of the company
  • Most cash plus shares wins

Components

Players
  • Cash
  • Shares: max. 50% of a company (60% with 2 players)
  • Privates
Companies
  • [SSF], [SWP], [HMQ], [VH], [ITC], [LG], [KR]
  • Float: 50% sold
  • Two bases: [LB] and [SP], with 2 transports each
  • Can hold shares in other companies
Bank and market
  • ₡12,000 bank
  • [IPO] and open market
  • New transports
Map
  • Minerals: value changes with tile colour, and some go down
  • [LB]: always 30. [SP]: 20, then 30 (operating round 3.1) and 40 (5.1)
  • East and west exits: 20, and +40 each if the route links both sides

Where the money goes

  • Players Companies Buying [IPO] shares
  • Players Bank and market Buying market shares and privates
  • Bank and market Players [SP] dividends, private income, sales
  • Bank and market Companies [LB] revenue, share issues, dividends on other companies' shares
  • Companies Bank and market Transports, tiles and stations

Phases

2
Start
2 · ₡120
Limit: 2 transports per base
3
1st 3-transport
3 · ₡150
4
1st 4-transport
4 · ₡240
5
1st 5-transport
5 · ₡500
2s rust
6
1st 6-transport
6 · ₡540
3s rust
10
1st 10-transport
10 · ₡730
4s rust
  • There's no choosing between paying out and withholding: what the [LB] earns stays with the company and what the [SP] earns goes to the shareholders.
  • The share price depends only on the [SP]: it rises with half the price, rises two spaces with double, and drops if it earns nothing.

A round, step by step

Illustrative example with 18xx.games rules, 3 players with ₡540 each. Minerals come out at random; values are the yellow-phase ones. We follow [P1] and the [LG] through the first turn: stock round, corporate round and two operating rounds.

  1. Initial auction The [RL] Phase 2

    Privates are auctioned as in 1830. [P1] takes the [RL] at face value, ₡60. It pays ₡10 per operating round and, owned by a company, places a permanent +20 on a mineral or a base.

    [P1] cash
    ₡480
    [LG] treasury
    —
    [LG] share price
    —
    [LG] transports
    —
  2. Stock round 1 Starting the [LG] Phase 2

    [P1] starts the [LG] at ₡90 and buys the president's certificate (20%) for ₡180. With incremental capitalisation, the money goes to the treasury.

    The company already has a station at its [LB] and another at the [SP] from the start.

    [P1] cash
    ₡300
    [LG] treasury
    ₡180
    [LG] share price
    ₡90
    [LG] transports
    —
  3. Stock round 1 Up to 40% Phase 2

    Over two more turns they buy two 10% shares from the [IPO] at ₡90. They hold 40%, but floating takes 50%.

    With 3 players nobody can go above 50% of a company.

    [P1] cash
    ₡120
    [LG] treasury
    ₡360
    [LG] share price
    ₡90
    [LG] transports
    —
  4. Corporate round 1 The company helps itself Phase 2

    In the corporate round, the [LG] issues a share to the market and collects ₡90 for it. That puts 50% outside the [IPO]: the [LG] floats.

    Until it floats, issuing doesn't lower the share price.

    [P1] cash
    ₡120
    [LG] treasury
    ₡450
    [LG] share price
    ₡90
    [LG] transports
    —
  5. Operating round 1.1 One tile from each base Phase 2

    The [RL] pays [P1] ₡10. The [LG] lays two tiles: one on a mineral hex next to the [LB] and another next to the [SP]. Mineral hexes cost ₡20 each.

    It can do two tiles or upgrades, but at most one from each base.

    [P1] cash
    ₡130
    [LG] treasury
    ₡410
    [LG] share price
    ₡90
    [LG] transports
    —
  6. Operating round 1.1 No transports Phase 2

    It has no transports yet: the [SP] pays nothing and the share price drops one space, from ₡90 to ₡80.

    [P1] cash
    ₡130
    [LG] treasury
    ₡410
    [LG] share price
    ₡80
    [LG] transports
    —
  7. Operating round 1.1 Two 2-transports Phase 2

    It buys two 2-transports at ₡120. It assigns one to the [LB] and the other to the [SP].

    Each base can hold 2 transports. Before running, one can be moved from one base to the other.

    [P1] cash
    ₡130
    [LG] treasury
    ₡170
    [LG] share price
    ₡80
    [LG] transports
    2 LB + 2 SP
  8. Operating round 1.2 The [LB] transport runs Phase 2

    Another ₡10 from the [RL]. The [LB] transport runs from the base (30) to an armalcolite mineral (40 in yellow): ₡70. Everything the [LB] earns stays in the treasury.

    [P1] cash
    ₡140
    [LG] treasury
    ₡240
    [LG] share price
    ₡80
    [LG] transports
    2 LB + 2 SP
  9. Operating round 1.2 The [SP] transport runs Phase 2

    The [SP] transport runs from the Space Port (20) to a helium-3 mineral (30): ₡50. That's paid out: ₡5 per 10%. [P1] holds 4 and collects ₡20.

    [IPO] and market shares get nothing.

    [P1] cash
    ₡160
    [LG] treasury
    ₡240
    [LG] share price
    ₡80
    [LG] transports
    2 LB + 2 SP
  10. Operating round 1.2 The share price follows the [SP] Phase 2

    ₡50 is at least half the share price (₡40), so it moves up one space: back to ₡90. Double (₡160) would have moved it up two.

    The [LB]'s ₡70 doesn't count toward moving the share price.

    [P1] cash
    ₡160
    [LG] treasury
    ₡240
    [LG] share price
    ₡90
    [LG] transports
    2 LB + 2 SP
  11. Operating round 1.2 The first 3-transport Phase 3

    The other companies have already bought the three remaining 2-transports. The [LG] buys the first 3 for ₡150 and puts it at the [SP]. Phase 3 begins: green tiles.

    [P1] cash
    ₡160
    [LG] treasury
    ₡90
    [LG] share price
    ₡90
    [LG] transports
    2 LB + 2 and 3 SP
  12. Towards stock round 2 What now? Phase 3

    In green, helium-3 goes up to 40 but armalcolite drops to 30: you need to think about which minerals to upgrade. In corporate round 2 the [LG] will be able to buy shares in other companies, which will pay it their [SP] dividends. From operating round 3.1 the [SP] will be worth 30.

    [P1] cash
    ₡160
    [LG] treasury
    ₡90
    [LG] share price
    ₡90
    [LG] transports
    2 LB + 2 and 3 SP

21Moon: The Race to Exploit Space — Summary

Capitalization type

  • Incremental capitalization: the treasury only receives the money actually paid for each share sold, both at IPO and in later issues.
  • Corporations use their own separated-treasury model (treasury_as_holding): shares bought can go directly into the company's own cash instead of the pool.

Floating percentage and per-player share limits

  • Floats once 50% of shares are sold (single threshold for every corporation)
  • No player may hold more than 50% of a single corporation; with 2 players the cap rises to 60%
  • Certificate limit per player: 2 players — 18; 3 players — 15; 4 players — 12; 5 players — 10

Starting cash by player count

  • 2 players: ₡600 starting cash (60% ownership cap instead of the usual 50%)
  • 3 players: ₡540 starting cash
  • 4 players: ₡410 starting cash
  • 5 players: ₡340 starting cash
  • The bank always starts with ₡12,000

End game triggers

  • A company goes bankrupt and only one solvent player remains: immediate end
  • Fixed schedule: the game always ends when operating round 11 (OR 5.3) finishes, regardless of the bank or trains

Number of phases

  • 6 phases (2, 3, 4, 5, 6, 10), triggered by the purchase of the first train of each type
  • Every turn combines a stock round, a "corporate" round (buying/selling between corporations) and two operating rounds (three in the last one)
  • The 7th corporation is held back and can't be founded until the 3rd stock round

Train list and prices

  • T2 transport — ₡120 (5 units; obsolete on the first T5)
  • T3 transport — ₡150 (4 units; obsolete on the first T6)
  • T4 transport — ₡240 (3 units; obsolete on the first T10)
  • T5 transport — ₡500 (2 units)
  • T6 transport — ₡540 (2 units)
  • T10 transport — ₡730 (unlimited)
  • The progression jumps straight from T6 to T10, with no T7/T8/T9

List of private companies

  • Old Landing Site (OLS) — ₡30 — places a black "SD" token on a mineral hex; can be sold to a corporation for just ₡1; gives rise to the OLS minor
  • UN Contract (UNC) — ₡30, revenue ₡5 — when bought by a corporation, lets its president add or remove a 2-6 train from the depot; closes on use; resold for ₡1-₡45
  • Space Bridge Company (SBC) — ₡40, revenue ₡10 — allows building across the Rift; ₡60 bonus once the connection is completed; resold for ₡1-₡60
  • Research Lab (RL) — ₡60, revenue ₡10 — places a permanent +20 marker on a mineral or base hex; resold for ₡1-₡90
  • Terminal (T) — ₡80, revenue ₡15 — teleports the terminal tile (X29) and places the cheapest base on it; resold for ₡1-₡120
  • Tunnel Company (TC) — ₡100, revenue ₡15 — once per game, exchange for a free pool share; also gives corporations a discount to 10 on mountain terrain; resold for ₡1-₡150

List of corporations

  • Shamsum Solar Farms (SSF) — home at D12
  • Suijin Water Plants (SWP) — home at C7
  • Hematite Low-G Mining and Quarry (HMQ) — home at D2
  • Varuna Hydroculture (VH) — home at G7
  • International Tritium Consortum (ITC) — home at I5
  • Lunar Geodynamics (LG) — home at I11
  • Kiviuq Rovertech (KR) — home at K9
  • All float at 50% and have a 50% ownership cap (60% in 2-player games); one of the 7 is held back until the 3rd stock round

Game-specific mechanics

  • Each hex's value depends on the mineral present (Source-X, Helium-3, Regolith, Armacolite, Magnetite); upgrading the tile changes the mineral's value, upward or downward depending on the type
  • Every company must run trains from both its own home base (LB) and the shared Space Port (SP, hex E9); revenue is split between the two circuits
  • ₡80 bonus for connecting the map's east and west exits on the same route; ₡30 bonus for reaching the terminal from the east
  • End-game bonus tokens at the map's four corners (NE/SE/NW/SW), awarded when a company connects both sides; worth ₡50 per share in the final scoring
  • The Space Port automatically upgrades (and rises in value) in operating rounds 3 and 5

Emergency sell

Unlike 1830, the corporation's own treasury shares must be issued to the market first, before anyone's personal cash is ever touched — trying to sell personal shares while the corporation still has issuable treasury shares isn't even allowed. Only once the corporation has nothing left to issue can the president sell their own personal shares of any company. A corporation forced to buy this way can only buy from the bank, never from another corporation, and unlike 1830, going bankrupt here doesn't end the game.

Comparison with 1830

1. Setting: lunar mining in the year 2117
1830 covers the northeastern US in the 19th century. 21Moon moves the same game skeleton into the future: companies don't transport passengers or classic goods, but instead mine critical minerals on the lunar surface during the year 2117.

2. End of game by calendar, not by bank or by trains
In 1830 the game ends when the bank runs out or the last available train is bought. In 21Moon the end is set by a strict deadline of 11 operating rounds in total, so there's no "dead queue" of passive turns waiting for something to happen: the game always closes at the same point on the calendar.

3. Hex value depends on minerals, which change with each tile
In 1830 a hex's value comes from the city it contains and doesn't change in nature. In 21Moon, the minerals present determine the hex's value, just like cities in classic 18xx games, but with a twist: when the tile changes (when it's upgraded), the mineral's value also changes, and depending on the mineral type, that change can be upward or downward.

4. Trains (transports) with their own progression: T2 to T6 and then T10
In 1830 trains follow a well-known 2-3-4-5-6-D progression. In 21Moon the "transports" go from T2 to T6 and jump straight to T10, and on top of that, T2s become obsolete when T5s appear (not T4s, as the intuitive equivalent would suggest) — a different obsolescence pace than you'd expect by analogy with 1830.

5. Two map "circuits": home base and shared Space Port
In 1830 all of a company's trains run through the same network connected to its own tokens. In 21Moon every corporation must run trains from both its own home base and the shared Space Port (a single hex used by every corporation), a dual-network structure with no equivalent in 1830.

6. Up to 7 corporations, with one held back until round 3
21Moon allows up to 7 simultaneous corporations mining the lunar surface, but one is deliberately locked out until the third stock round. 1830 never withholds any of its companies this way.

7. Rules engine recognizable from 1830 and 1846
Despite the science-fiction setting, players experienced in 18xx usually quickly recognize how 21Moon works, since its basic rules closely resemble those of 1830 and 1846: stock rounds, operating rounds, share and train purchases.

8. A pure science-fiction theme, with no precedent in 1830
While 1830 recreates the real history of the North American railway boom, 21Moon invents a near future of lunar resource exploitation, with no direct historical basis at all.

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A term you do not recognise? They are all explained in the 18xx glossary. Glossary →