Last Updated on April 14, 2025 by The Official Game Rules Team

Peptide: A Protein Building Game is a biology-themed card game where players build peptide chains by linking Amino Acids using RNA and energy resources. Choose Organelle cards to gain actions or resources, and compete to score the most points before the STOP Codon ends the game.

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How to Play Peptide: A Protein Building Game

Game Summary

In Peptide, your objective is to build a Peptide Chain by linking Amino Acid cards in a row. To do this, players select Organelle cards each round, gaining a mix of resources and actions. Points are earned based on the Amino Acids added to your chain. The player with the highest total score at the end of the game wins.

Components

30 Organelle Cards

6 Vacuole
6 Ribosome
6 Nucleus
6 Mitochondria
6 Amino-Acyl

27 Amino Acid Cards

20 Amino Acid
6 Methionine (Start Codon)
1 STOP Codon

48 RNA Cards

12 Adenine (green)
12 Guanine (blue)
12 Cytosine (red)
12 Uracil (orange)

Additional Cards

6 Reference cards
3 Bonus Point cards
1 First Player card

32 ATP Energy Tokens
Used only in the Advanced game. Exclude them for Basic gameplay.

12 Vacuole Track Markers
6 Vacuole Track Cards

Game Setup

Before you begin, choose between Basic and Advanced difficulty. Advanced mode adds strategic depth and uses additional components explained in its section.

Each player receives:

2 ATP tokens
1 Reference card
1 Methionine (Start Codon) card
(Return all unused copies of these to the box.)

Separate the Organelle, Amino Acid, and RNA decks.

Prepare the Organelle Deck

Shuffle and place it face down near the left side of the play area.
Place all ATP tokens above this deck.
Stack Bonus Point cards (+3 on top, then +2, then +1) to the left of the ATP tokens.

Prepare the Amino Acid Deck

Find and set aside the STOP Codon card.
Shuffle the remaining 20 Amino Acid cards.
Remove a number of cards based on player count:
- 2 players: remove 5
- 3 players: remove 6
- 4 players: remove 2
- 5+ players: remove 0
  (Return removed cards to the box.)
Randomly insert the STOP Codon among the bottom 4 cards.
Place this deck face down to the right of the ATP pile.

Prepare the RNA Deck

Shuffle and place it face down next to the Amino Acid deck.
Reveal the top two RNA cards and place them face-up beside the deck.

Starting the Game

The youngest player takes the First Player card.
You’re now ready to play!

Table Layout

Bonus Point stack
ATP supply
Organelle and Amino Acid draw decks
RNA draw deck and two face-up RNA cards
Leave space beside your Methionine card for your growing Peptide Chain
Leave room for Organelle and RNA discard piles

Gameplay Overview

The game progresses in rounds until the STOP Codon is drawn. After that round, one final round is played before scoring.

Each round has two phases:

Organelle Selection – Players choose Organelle cards for actions/resources.
Organelle Resolution – Players use the selected Organelle cards.

ATP Actions

Players may spend ATP tokens on their turn during either phase to take optional ATP actions (see ATP Actions section below).

Phase 1: Organelle Selection

Deal 2 Organelle cards per player face-up into the Organelle Field (for 2 players, always deal 6). Stack duplicates.
If the Organelle deck is empty, shuffle the discard pile to form a new deck.

Starting with the First Player and going clockwise, each player selects one Organelle card. Repeat the process a second time so each player has two cards.

Alternative Selection Options:

Take an Organelle face down to gain 1 ATP during Phase 2 instead of performing its action.
Choose the First Player card (only once per round). You immediately become the new First Player.

Any unselected Organelle cards are discarded at the end of the phase.

Phase 2: Organelle Resolution

Each player, in turn order, resolves both of their Organelle cards in any order. Used cards go into the Organelle discard pile.

If a card was taken face down, discard it and gain 1 ATP.

Organelle Actions

Mitochondria – Gain ATP
Gain 2 ATP tokens from the supply.

Nucleus – Draw RNA Cards
Choose one:

Take 1 face-up RNA card and replace it.
Draw 2 RNA cards face down, keep 1 and discard the other.

Vacuole – Gain RNA + ATP
Draw 1 RNA card from the deck and gain 1 ATP.
In Advanced mode: optionally increase your RNA or ATP storage limit by advancing your Vacuole Track.

Amino-Acyl – Gain Amino Acid
Pay 2 ATP. Draw 2 Amino Acid cards, keep 1 and place the other back on top of the deck.

If one of them is the STOP Codon, reveal it and place it in the center of the table. Keep the other card.

Ribosome – Add to Your Chain or Make Permanent
Choose one:

Option 1: Add to Your Chain
Pay 1 ATP. Match one Amino Acid from your hand with 3 matching RNA cards.

Place the Amino Acid to the right of your chain (starting with Methionine), and the RNA cards below it.

Option 2: Make Permanent
Pay 1 ATP. Flip your leftmost face-up Amino Acid card face down.

Discard its RNA cards.
If Bonus Point cards remain, take the top one.

Making a Match

Each Amino Acid card shows a 3-letter RNA code on the bottom.
Match each letter to an RNA card:

A = Adenine
C = Cytosine
G = Guanine
U = Uracil

Examples:

Arginine (CGA) → 1 Cytosine, 1 Guanine, 1 Adenine
Threonine (ACC) → 1 Adenine, 2 Cytosine

ATP Actions

You may take these at any time during your turn:

Reset RNA Field: Pay 1 ATP to discard both face-up RNA cards and draw two new ones.
Reset Organelle Field: Pay 2 ATP to replace all Organelle cards.
Select Twice: Pay 3 ATP on your first pick to select both Organelle cards consecutively (you skip your second turn that round).

ATP tokens are paid back into the general supply.

Winning the Game

Once the STOP Codon is revealed, finish the current round and play one final full round.

Scoring:

Each Bonus Point card: value shown
Permanently connected (face-down) Amino Acids: full value
Face-up Amino Acids in your chain: half value (rounded up)
Amino Acids in hand with full RNA match: 1 point
Amino Acids in hand without a match: -1 point each
(RNA cards can only be used once for these matches)

The player with the highest score wins!

Peptide: A Protein Building Game combines strategic card drafting with real biological concepts, making it both educational and engaging. By managing resources and timing your actions, you’ll compete to build the most efficient and valuable Peptide Chain. When the STOP Codon appears, only the most well-constructed chain will lead to victory.