This reminds me of Genshin Impact where you at some point collect evidence and connect them together to later refute claims in some kind of court. Basically, you choose the right evidence to refute some given claim. I really like that part of the game, looking forward to seeing a whole game about that!
But yeah, begin simply with some kind of collect-the-points game. Extend the game to give every point unique properties, these are evidence. Establish an inventory for the evidence, there is some source code for implementing game inventories, look it up.
Of course, another way to do this is to implement some kind of story/quest chain. You are presented with a story "you are in a room blahblahbla" and get some choices such as "look under the carpet", "investigate the sofa", "go to next room"... There should be some story/quest tutorials too, how to make choices impact on the story and so on.
