LA Noire is an open-world Los Angeles 1960's detective life game. Different from other famous Rockstar games where you are free to kill people, here you're a good man serving the public by solving murder, theft and drug cases.
Like other open-world games, you can roam around here. You can drive thru people but they are skilled in tumbling. Response police radio calls and apprehend criminals and suicidal attempts (side missions). You can also grab other cars by simply presenting your badge to the drivers, though you can only ride cars and delivery trucks, nothing else.
The game runs only to (mostly) murder cases, roam around the crime scene on foot and search for clues and evidence, a chime will sound if an evidence is nearby. After you've found all the evidences, you'll interrogate witnesses and suspected criminals. This is the most difficult part, this makes the game very difficult because you have to analyse if the person you're interrogating is telling the TRUTH, LIE, or if not sure, you can DOUBT. Analyse the facial expressions of the person since it may lead you to correct answer, but sometimes, the facial expressions also gives you the wrong answer (assume that the suspect is an expert liar). If you chose LIE, you should be prepared to choose the required evidence. Sometimes, you may also be mistaken that the person is telling the truth, but the programmed facial expression seems tensed or troubled, so you chose LIE or DOUBT. Also, there are cases that you can imprison a wrong person. So it is really very difficult.
(caution, CHEAT: if you got the wrong answer, quit game to main menu, then resume. You will be at the entrance of the area where you last auto-saved. Try and try until you get the correct one. Do not restart case.)