This replaces the key card, so a standard Codenames box plays Duet. Nine agents each, three of them shared — fifteen to find between you.
Two phones? Send your partner the link, or read them the six characters to type in. Same code, same key card. One phone? Pass it across and reveal one side at a time.
Setup with a standard Codenames set
Deal 25 word cards face up in a 5×5 grid. Leave the box's key cards in the box — this is the key now.
Sit across the table and keep seating on opposite, or sit side by side and switch it. Either way you both read the grid the same way round.
Each of you reveals your own side only: 9 agents, 3 assassins, 13 bystanders. Some of your agents are your partner's assassins.
Take turns giving a one-word clue and a number. Your partner guesses against your side of the key, and you tell them what they hit.
Agent → cover the word with any agent card from the box; red or blue, it just means found. Bystander → cover it with a tan bystander card and your turn ends.
You get nine turns between you. Find all fifteen agents to win. Hit an assassin and the game ends right there.
Hand over the device
Side 2
Only operative 2 sees this key. Make sure the other player is looking away.