I bought Arkham City when it came out, and played it to death. I didn't go as far as Perfect Knight; that seemed far too fiddly, but I did want to get all the Riddler challenges done and that I managed. Grinding his smug face in the dirt was very satisfying! Plus, unlike the previous game Arkham Asylum, there was a good reason to get the Riddler, since he kidnapped several innocent civilians and threatens to kill them unless you solve his puzzles. Along the way you, as Batman, have to figure out several hundred riddles, beat individual challenge rooms, and finally confront the green weasel in his lair. It's one of several potential side missions in which you track down leads to solve the mystery before it's too late, and while some of those (like Zsasz) are more acrobatic, the Riddler missions are about 50/50 brain power to gadget use.
I spent a chunk of Sunday playing it again, since an Xbox blowout reset the game. All the Riddler challenges reappeared, giving me a second chance to knock them down again. Tracking down those clues was a big part of the fun for me the first time around, and it's been just as enjoyable the second time running.
However it made me think about clues in detective-style settings. The classic of course is Holmes' inductive reasoning, as follows:
My eyes tell me that on the inside of [Watson's] left shoe, just where the firelight strikes it, the leather is scored by six almost parallel cuts. Obviously they have been caused by someone who has very carelessly scraped round the edges of the sole in order to remove crusted mud from it. Hence, you see, my double deduction that you had been out in vile weather, and that you had a particularly malignant boot-slitting specimen of the London slavey.
Which is fine as far as it goes, but it relies on two assumptions. First, that the parallel cuts can only have been caused by a boot-scraper. That's something the modern reader has to take on faith, since few people now living really know what a Victorian era boot-scraper is or why it would cause parallel cuts as opposed to any other kind. However if there is any other way that parallel cuts of that type could have been caused, the boot-scraper theory is in danger of falling flat, which may mean the vile weather theory is flawed. Second, it assumes that a Doctor's boots can only have been scraped by his servant. That's likely, of course, but it's also possible they were scraped by the Doctor, his wife, or a third party - particularly since as a Doctor he's likely to be visiting other people's houses, and dealing with other people's servants. As it happens Holmes is right on the money, but it could easily have gone the other way.
Which is the big problem with fictional detectives. Agatha Christie alludes to this more than once, using her character Ariadne Oliver as a mouthpiece. Oliver is a detective story novelist, and frequently grouses at how stupid she was to make her main character a Finn when she knew almost nothing about them, but she also has a lot to say about the perils of clue creation. A novelist can make a blowpipe one foot long even though it really ought to be four and a half foot. A novelist can tell lies to help the plot along, by insisting that a clue is a clue when in fact it means nothing, or the opposite of its apparent meaning. Dorothy Sayers does much the same thing with her character Harriet Vane, particularly in Have His Carcase. In that novel Harriet is supposed to be working out a plot for her own mystery novel when she stumbles across an actual murder, and Harriet spends a lot of her writing time grumbling about getting the timetable right for the trains in her novel, for fear that any mistake will be picked up on by nitpicking readers.
The bigger problem is this: the reader expects a Clue to be a Clue, to have a definite meaning in and of itself. There can be no shades of grey. It's all part of a larger puzzle, and if the pieces are put together in the correct order then the puzzle can be solved. It's a genre convention that's wide open to parody since it assumes a kind of story structure that's almost impossible to envisage in real life. Real life is messy. Trains don't run on time. Blowpipes can be novelty sized. Mysteries can't be puzzled out through inductive reasoning alone, though inductive reasoning may certainly help.
In the Death Investigator's Handbook, it's all about procedure. Evaluating the crime scene isn't even the first point on the checklist; it's under section C, where A is about establishing the perimeter and B is about contacting the necessary responders. Examining the body doesn't happen until way, way down the checklist, where in a novel it would be the very first thing the detective looks at. I'm not even sure the word Clue is ever used in that book; I can't be certain since there isn't an index in my 1993 edition. It's all Evidence, and one piece of evidence in itself means nothing. It's the totality that means everything.
'What were the victim's activities, how was the victim selected as a target, and what was done to the victim are three areas of consideration. The significance of the scene, how it was selected and the evidence it has provided are other courses whch need to be developed . . .'
It's nice to pretend to be Batman for a while, but Batman is fiction, and the puzzles he faces aren't tied to reality in any meaningful way. That's not why they're there. They exist to provide an intellectual challenge in an artificial world. All Clues are like that. They provide a challenge, but they oughtn't to be taken too seriously.
After all, they're only make-believe.