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Put on a hazmat suit, roll the dice and prepare to compete in nuclear waste enrichment. Critical Mass puts you in control of a nuclear power plant in the competition to enrich nuclear waste.

Goal of the gameYour objective in the game is to manage your power plant better than your opponents. To do that, you must roll dice and use their properties to create fuel cells (victory points).

The first player to have 5 fuel cells wins the game.

Fuel cells are created when at least 2 different radioactive dice are fused in the power plant’s reactor. Only radio-active dice can be placed in the reactor, so it is necessary to enrich the dice in the power plants centrifuge, before placing them in the reactor.

Game Contents56 dice (nuclear waste)• 16 green• 12 red• 12 blue• 8 purple• 8 white

4 player mats (power plant)20 fuel cells (victory points)

1 dice bag

The Nuclear WasteThere are 5 different types of nuclear waste in the game:

All dice share 3 symbols:

Uranium

Plutonium

Radioactivity symbol. When rolled, the die may be placed in the reactor.

Ray gun symbol. When rolled, the die may be placed in any ray gun slot.

Ionizer symbol. When rolled, the die may be placed in any ionizer slot.

Neptunium

Curium

Thorium

2 -4 30 - 45 min.

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The Power PlantEach player mat depicts a power plant with the following ele-ments:

1. 3 ray gun slots. Only dice with the ray gun symbol can be placed here.

2. Reactor. Only dice with the radioactive symbol can be placed here.

3. 3 Ionizer slots. Only dice with the battery symbol can be placed here.

4. Centrifuge with 4 connected depots.

5. Fuel cell track

Distribution of the symbols

Uranium

Plutonium

Neptunium

Curium

Thorium

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Game Setup• Each player takes 4 green dice from the dice bag.

• Each player randomly draws 1 die from the dice bag.

• The 4 green dice are placed in any one depot and the randomly drawn dice are placed in any 1 ionizer slot, with the battery symbol facing up. This dice will power the centrifuge.

• Place the remaining dice on the table in front of the player boards. This is the shared dice pool.

• Place the fuel cells anywhere in the shared pool.

• Pick a starting player and proceed in clockwise order.

A Game TurnA game turn is divided into 4 actions. In a turn, each play-er may only choose up to 2 out of 4 possible actions.

The actions must always be executed in the order 1 through 4.

1) Fire ray gun

2) Activate Reactor

3) Place/Remove dice in the Ionizer

4) Activate Centrifuge

Example: If a player chooses action 1 and 3, he must fire the ray gun before placing dice in the ionizer.

Note: On the first turn, it is not possible to select action 1) or 2)The number of dice in a

game is determined by the number of players.

In a 4 player game, all the dice are used.

For each player less in the game, remove 4 green dice, 3 red dice,3 blue dice, 2 purple dice,2 white dice before setting up the game.

Game setup for a 2 or 3 player game

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Explanation of the actions1) FIRE RAY GUN

If you have placed 1 or more dice with the ray gun symbol in any of your power plant’s ray gun slots, these dice can be used as ammunition when firing the ray gun.

• Each time you fire the ray gun, the die used loses its radioactivity and is placed in your depot.

• You may fire up to 3 times in the same action, if you have enough dice placed in the ray gun slots.

• You may target any 1 of your opponent’s radioactive dice, placed in his:

a. Ray gun b. Reactor c. Ionizer

• Target opponent die loses its radioactivity and is placed in his depot.

• You cannot target the same color die as the one you are using, i.e. a blue die cannot target a blue die etc.

Example of firing the ray gunPlayer A has 2 red and 1 blue dice ready in his ray gun. Player B has 1 red die placed in his ray gun and 3 blue dice in his reactor. Player C has 1 green die placed in his ionizer.

Since Player A cannot use his red dice to target Player B’s ray gun, he instead use his blue die to eliminate Player B’s red ray gun die, which loses its radioactivity an is placed in Player B’s depot.

Player A still has 2 shots left and now targets Player C’s green ionizer die with one of his red dice. Player C’s green die loses its ability to pow-er his plant, and is placed in his depot.

Now Player A could target his last shot on one of Player B’s blue reactor die, but he decides to save it for later.

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Example of splitting dicePlayer A has 2 blue radioactive dice in his reactor.

There are 4 blue dice in the pool, so Player A takes 2 of those blue dice from the pool and places them in his depot.

2) ACTIVATE REACTORTogether with the centrifuge, the reactor is the backbone of your power plant. When activating the reactor, each die placed here offers you 3 possibilities.

The possibilities are: • Split die• Decay die• Utilize die radiation.

Let’s have a closer look at these possibilities:

Split die

To split a die is to grow in number.

Any radioactive die can split itself into a copy of the same die, as long as that color die is available in the shared pool of dice, placed in front of the player’s power plants.

When splitting a die, it loses its radioactivity and is placed in the player’s depot along with the gained “copy die”. The 2 blue dice used to perform the action are no longer radioactive

and are placed along with the other blue dice in the depot.

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Example of decayPlayer A has a green and a blue die in his reactor, but wants a red and purple die.

There are red and purple dice available in the pool. He decays the green die into a red and the blue die into a purple (the order is irrelevant).

Decay die

Decaying is the mechanism behind atomic change.

Any radioactive die can decay into any other color die, as long as that color die is available in the shared pool.

But decaying comes with a cost, since the decayed die must be paid to the player pool.

The newly gained die is not yet radioactive, and is placed in the depot.

The green and blue die is exchanged from his reactor with the red and purple, which are placed in each depot.

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Utilize dice radiation

When utilizing the radiation of the dice, your power plant gains special abilities this turn.

The abilities depends on what kind of dice you utilize:

• Plutonium: You may exchange your utilized red die with any die from target opponent depot. Target oppo-nent must have available space (a free depot or a depot containing dice of that same color) to receive your red die and you must have available space to receive the die you exchanged with him.

• Neptunium: For each blue radioactive die utilized, you may roll 1 additional time, if you select the “Activate Centrifuge” action in this turn. The utilized die loses its radioactivity, and is placed in your depot.

• Curium: For each purple radioactive die utilized, you may add any 1 additional die from your depot to your roll, if you select the “Activate Centrifuge” action in this turn. The utilized die loses its radioactivity, and is placed in your depot.

• Thorium: When utilizing the radiation of the white die, you activate its special decaying abilities, and it becomes a fuel cell. The utilized white die is placed in the shared pool.

• Uranium: The radiation of the green uranium dice cannot be utilized to gain special abilities.

Note: There is no limit to the number of dice that can be split/decayed/utilized during an activation of the reactor.

Nor is there any limit to the order in which the player must split/decay/utilize.

Example of splitting, decaying and utilizing in same actionPlayer A has 4 blue dice in his reactor, 2 green dice in a depot and 1 purple in his ionizer. He starts by decaying 1 blue die into a red from the shared pool. The red die is placed in his depot. He then splits one blue die to regain the blue he just paid to the pool. He leaves 1 blue die in the reactor for later, and finally he utilizes the radiation of the last blue die.

The utilized blue die is placed in the depot, and when activating the centrifuge in the next action, he decides to roll with his green dice, and may now roll 2 times.

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3) PLACE/REMOVE DICE IN THE IONIZERThe Ionizer functions as a power generator to the Centri-fuge.

Without at least 1 die in any of the ionizer’s 3 available slots, the centrifuge cannot function and nuclear waste enrichment is impossible.

Dice placed in the ray gun and reactor are already ren-dered radioactive, thus the ionizer only delivers power to the centrifuge. It is always possible to activate the ray gun and reactor independently from the ionizer.

In the case a player is targeted by an opponent’s ray gun, he can find himself without any dice in the ionizer to pow-er the centrifuge. He then has the option to manually put up to any 3 dice from the depot(s) into the ionizer.

Using the centrifuge does not deplete the dice placed there. Radioactive dice placed in the ionizer stays there until they are removed by the player or targeted by an opponent’s ray gun.

During a turn, it is always possible for a player to use 1 of his 2 actions to place and/or remove up to any 3 dice in the ionizer.

4) ACTIVATE CENTRIFUGEThe centrifuge is the backbone of nuclear waste enrich-ment. When activating the centrifuge, the player simply picks up all the dice from 1 of his depots and rolls them.

The centrifuge functions in conjunction with the 4 con-nected depots.

• When not radioactive, dice must always be placed in the depots.

• Only dice of the same color can be placed in a depot• All dice of the same color must be placed in the same

depot• There is no limit to the number of dice placed in a

depot.

When activating the centrifuge, a player must abide by the following rules:

• The centrifuge can only be activated if there is at least 1 die placed in the ionizer.

• The centrifuge can only be activated one time per turn, unless 1 or more blue radioactive die was utilized in the reactor earlier this turn.

• The centrifuge can only enrich dice of the same color, unless 1 or more purple radioactive die was utilized in the reactor earlier this turn.

• Activating the centrifuge is always the last action of a player’s turn.

After rolling, the player may allocate the radioactive dice to their equivalent location in the power plant.

The enrichment is always optional, meaning it is up to the player to decide how many dice he will allocate to the reactor, ray gun and ionizer.

Dice not allocated are simply put back into the depot.

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Creating Fuel Cells and winning the gameFuel cells represent victory points. To create fuel cells, a player must fuse at least 2 radioactive dice of different color.

In exchange for the fuel cells, the dice are paid to the shared pool.

While the fusing of dice into victory points only happens in the reactor, it does not count as an action and can there-fore happen even immediately after dice are allocated.

It is always up to the player to decide if, when and how he wants to fuse the radioactive dice into fuel cells.

The fusing of radioactive material into fuel cells is more efficient if the material is diversified. 3 different color dice can therefore be exchanged with the shared pool for 2 fuel cells etc. It is theoretically possible and allowed to fuse 5 different color dice into 4 fuel cells.

Note: Exchanging the white die into a fuel cell is part of uti-lizing the radiation of that die, and must always happen as part of an action in the reactor. The white die can therefore not be enriched in the centrifuge and utilized in the reactor in the same turn (since the actions always must be executed in the order 1 through 4).

However that does not mean that a white die cannot be fused with another color die into a fuel cell. In that case the creation of fuel cells takes place as normal.

Fuel Cells are placed on the fuel cell track. Any player who creates 5 fuel cells is immediately declared the winner of the game.

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4x

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Different color dice Fuel Cells

CreditsGame design: Morten Weilbach

Game testers: Daniel Skjold Petersen, Ole Steiness, An-dreas Andersen, Erik Modin, David Nielsen, Tim Kaas, Johannes Thorup Juul, Troels Vastrup, Johannes Følsgaard, Johannes Sjolte, Asger Sams Granerud, Ole Palnatoke An-dersen, Jeppe Norsker, Emil Larsen, Kasper Weilbach

Icons: Game-icons.net, Flaticons.net

Thank You: Jeppe Norsker for preparing dice icons.

Contact: mweilbach@hotmail.com

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Turn reference1) FIRE RAY GUN

• Target any 1 of your opponent’s radioactive dice, placed in his:

a. Ray gun b. Reactor c. Ionizer• You may fire up to 3 times in the same action, if you

have enough dice placed in the ray gun slots.

2) ACTIVATE REACTOR• Split die• Decay die• Utilize die radiation.

Split die: All enriched dice can be split into a “copy” of itself.

Decay die: All dice can decay into any other die, if available in shared pool.

Utilize radiation:• Plutonium: exchange utilized die with target die from

opponent´s depot.• Neptunium: For each utilized, roll 1 additional time

when activating centrifuge.• Curium: For each utilized, add any 1 die from depot to

roll, when activating centrifuge.• Thorium: When utilizing, exchange for 1 fuel cell.• Uranium: Cannot be utilized.

3) PLACE/REMOVE DICE IN THE IONIZERAdd/remove any dice to and from your depot(s) to the ionizer.

4) ACTIVATE CENTRIFUGE• Can only be activated if there is at least 1 die in the

ionizer.• May only roll with 1 color die (unless 1 or more pur-

ple die was utilized this turn)• May only roll 1 time (unless 1 or more blue die was

utilized this turn)• No restriction on amount of dice that can be rolled at

a time• Enrichment is optional. Player allocates result by own

choice