A hidden role game is one in which a player or players, selected out from the group, have some element of their play goals altered in a way that sets them apart from the group. Hidden role games are not always asymmetrical team games, but they often are.
Hidden role games are most obviously useful for making deducing who is on what team part of the game. This is the basic core question of games like Secret Hitler and The Resistance: Avalon – the gameplay is almost completely about working that out.
Nonetheless, Hidden Role is not a mechanic limited to this. You can use it as part of a larger game, where for example, players are largely competing to put together a set of resources, while one player is trying to prevent that without being noticed. You can even make hidden role games where the hidden role is itself a power – look to games like Maskerade and Coup.
Finally, Hidden Role games can be made co-operative as a way to ensure quarterbacking can’t or won’t happen. Players can’t actually determine an optimal path of what players should or shouldn’t do without literally knowing what they actually can do.
Hidden role games can kinda bottle anxiety. It can be exciting and thrilling to play a hidden role game with your needs and wants a secret, trying to keep from being caught, but it’s stressful.
Hidden role games also tend to be comparable to one another.
Maskerade, The Resistance, One Night Ultimate Werewolf, and Battlestar Galactica.
btw, I have no idea where that header graphic is from but it looks like it’d make a great hidden identity game