I spend roughly half my waking hours thinking about detectives, watching detectives on TV and reading about detectives in books. The other half of my waking hours are spent very specifically thinking about what a detective game might be like. How do you create a mystery which is compelling for players to deduce the answers to themselves, without being handheld and thus making the mystery dull and rote?
Where's An Egg? has an answer. It was released in 2007, was sort of made by a fictional game developer, and is about deducing the location of an egg. You can play it in your browser and get the measure of it in ten minutes, and you should.
Your aim in Where's An Egg? is to find an egg. You have a map of locations you can visit, and at each location you'll find a person and an object. You can then question the people you meet. It's all conveyed via symbols, with each person and object you see increasing the vocabulary of questions you can ask.
So you might meet a bald man with a plant. "Egg?" you ask. He responds with a picture of a person, location or object, representing where he thinks the egg is. The trick is that he could be lying, or mistaken, and the egg is in a different place every time. You need to work out who is telling the truth and who is lying by asking people different questions, and then corroborating their answers by visiting new locations and questioning new people.
In other words: detective work.
"Strawberry?" "Red hat man." "Red hat man?" "Forest." No he's not! YOU LIE.
When you think you've found the person with the egg, you can shoot them. Get it wrong three times and you go to jail, but get it right and you're given a medal for finding the egg. It helps to take notes, I found. Mine all read like, "BLUE CAP thinks egg is at furnace. Thinks strawberry is at furnace. Jogger is at furnace." and "SCRAGGLE is wrong about everything. Says egg is where she is?"
Do you remember all those scenes in which Columbo would scribble something in a tiny notebook while questioning a suspect? This is what he was writing.
Where's An Egg? won't take you long to play, but it's great. It feels like you're solving mysteries in natural ways, using your own reasoning and fact-finding. It was made by Videlectrix, the developer within the Homestar Runner universe who make all the games that turn up in Strongbad cartoons. That also means they make real games, so I probably shouldn't call them fictional. John interviewed them here.