I like Gumshoe games. I own Trail of Cthulhu, The Esoterrorists and Fear Itself, and plan to invest in Mutant City Blues at the very least.
I like the investigative slant to the games, especially as the systems provide a fit for purpose medium for playing games that ape popular TV shows: CSI, Criminal Minds, The Mentalist, X Files et al.
I really appreciate a good cop drama / murder mystery, especially the quirky end of the spectrum.
I do have a problem, though, and its nothing to do with the system. It's about how you play the game.
Many crime dramas, at one point or another, will set a trap for the bad guy. The trail of clues has led as far as its going to, and the detectives are now at a loss.
Enter the maverick investigator, who creates an elaborate and entertaining trap for the killer, one designed to identify the perpetrator and separate them from the pack of suspects. This device is used almost weekly in The Mentalist.
How could you do this in a game? As a device, its fun, dramatic and rewarding, and a massive narrative contrivance.
For it to exist in a game, a number of things need to happen.
The plot must have presented enough clues and detail to allow the set up.
The GM must be willing to run with such a device, and able to think on their feet fast enough to do so
The players must be creative enough to coke up with a workable model, and have gathered enough evidence already to create such a trap.
As it stands, the missing ingredients that prevent such devices occurring in my games are, unfortunately, my ability as a GM to line up the clues and run with such a high degree of player creativity.