You play as a detective sent to hunt down clues and build a case against a vigilante murderer. You're sent out to various locations to collect evidence, piece together torn documents, dust for fingerprints, and to do various other crime-solving activities. It seems the majority of the game has you doing a picture search to find objects on your list just like in those Highlights magazines you find in the dentist's office - it's very detective-y.
Why is there a cane on the roof? Why are there scissors glued to that wall? What the hell is all this crap doing here in the middle of the park? Righteous Kill evokes a number of questions, but few are about detective work. In the picture-searching levels, there's junk everywhere. It's the same junk in every location too, so even in a hospital room there will be hammers, scissors, and various other items just strewn about. But for some reason, you've got a list of what evidence you need to gather. You know for sure you're looking for 2 canes, a trowel, and 3 potted plants. You just don't know why.
There are various other types of games. One has you playing a "hacker" role, where you have to put up firewalls to trap the suspect's - ok I can't make myself finish this sentence. Suffice to say it's a game of placing tiles in order to block the opponent in. It's not very difficult, but it is a change of pace.
The serious tone of the story elements and the childlike simplicity of the gameplay really clash here. You'll get done with a matching game, and then suddenly another murder takes place even though you've apprehended the suspect! Don't get the idea that you'll be solving murder mysteries though: the game is all mini-games and matching puzzles. There's no Sherlock Holmes element here at all.