Game in a Game (minigames implementation)

Hello. How would one implement minigames in a multiplayer game - such as tic-tac-toe or other boardgames? The goal is to find out an optimum approach like is there some layering thing or should the gamemode change or something else.

Download content examples, there in demo for input is game in game.
And multiplayer game in game, you will have headache with this.
Aslo how advanced in unreal and multiplayer are you, i am not sure what kind of answer you need.