Spy Party is a one-versus-one game about observing behaviour. One player is a spy at a party among many computer-controlled guests, with a list of missions. The other player is a sniper who must spot the human-controlled spy by watching the way they are moving and interacting.

The player controlling the spy must complete various tasks, like planting bugs, finding microfiche, making contact with other guests without giving away who they are. The player controlling the sniper, must observe all the guests through the lens of his gun and take a single shot when they are sure they have found the spy.

While most spy games have you machine-gunning stuff, blowing things up, and driving fast, SpyParty has you hide in plain sight, blend into a high-society cocktail party, deceive your opponent, and detect subtle behavioural tells to achieve your objectives and not get shot.