A hybrid board game.
When the game starts, there are no specific rules or actions. Instead, on your turn, the smartphone gives a list of actions you can currently do! You simply pick one or execute one.
(If possible, one could also require all players to use their phone. This way, they can see their actions in advance and plan for it. Saves time.)
The goal of the game can be anything, but the phone represents someone whispering instructions behind the scenes. This lends itself best for a kind of improvisation party game about reacting to prompts or trying to convey a secret word or something.