Codenames: Deep Undercover is an adults-only, mature version of Codenames using the same popular game mechanics, but introduces all-new words, packaging, "by-standers” and art. A new twist is added with the inclusion of blank cards, allowing players to introduce their own words to the game.

The two rival spymasters know the secret identities of 25 agents. Their teammates know the agents only by their CODENAMES. The teams compete to see who can make contact with all of their agents first. Spymasters give one-word clues that can point to multiple words on the board. Their teammates try to guess words of the right color while avoiding those of the opposing team. And everyone wants to avoid the assassin!