Goose Game, but instead of a horrible goose you are a good dog whose job it is to break up fights at holiday parties. Let's game it out.
Simulated people will run through the motions for a party. Each guest will have a set of desires and some personal goals to achieve. For the sake of gameplay, everyone that can see the dog (player) will attempt to intervene when the player is misbehaving, rather than deferring to a host or someone else.
Something visually simple with bright colors and simple geometry. This game should be very easy on system resources and should operate smoothly on low-resource machines or mobile devices. One option:
High-fidelity, cheerful music with cute sound effects. Human speech and communication should _not_ be real human speech, but should be some sort of non-lexical vocalization like Simlish.
Fundamentally, the interpersonal interactions will drive the game. For replayability (and developer sanity) it is desirable to have conflicts emerge naturally from NPC interactions. Additional household events can add color or fun as discoverables, but the most fundamental piece of the game is the temperature of discourse.