Welcome to the Interpol: The Trail of Dr. Chaos walkthrough.
Have you ever sat in a doctor or dentist's office and looked over their waiting room magazines? If so, you might have seen a magazine for children. This magazine likely included a picture comparison to spot the difference, or one where you had to find items. This is basically what the entire game is about. If you had an easy time with those, you'll have an easy time with this game. The game is an easy completion, but can become incredibly frustrating if you always hated those types of puzzles.
If you aren't running away by now, let's get on with the story, or what there is of it.
The premise of this game is that you're given a picture, and told to find a certain amount of items within. You do this by highlighting the object and clicking 
. The pictures do change, adding and removing items depending on what it asks you to find. The items, however, are always in the same place within the picture when you're told to find them. So if you're told to look for a caterpiller, you'll always find it in the same place on the picture. This doesn't apply to bonus items, which provide extra points and have several different places they can spawn.
The missions each have a time limit of thirty minutes. This is usually a generous amount of time. There's a penalty if you start spamming the button to find an object you're struggling in. Too many attempts in a short period of time, and the clock takes time off. Each map gives a certain amount of hints, but you won't be allowed to use them if you intend to get the achievements. There are several different city locations, and as you chase the criminals, you'll be sent to all of them.
You must not use any hints as you progress through the story. Even if you have a hard time with a particular item, resist the temptation. If you accidentally use a hint, you need to finish the city and then immediately restart it. The game doesn't record where you might have used a hint, and you need to complete all cities without using them.
You'll start in San Francisco, and you'll be coming back to this city in the end. The bonus item in this city is the joker card, a white card with a symbol directly in the middle. Your first achievement will come when you complete the first city location in San Francisco. Take your time in the first location. Find three objects required without clicking on them, and then quickly click on all three of them within five seconds.
Once you do, finish the mission, making sure you find all three joker cards before the last item is found. If you need help getting a good idea on where things are, there are pictures near the end of the walkthrough of San Francisco that will help show where some items are.
Finder's KeepersFound all 8 Items in a City Location in the Single Player or Co-Op Mission
Make sure you find all three joker cards in each city location, and use no hints. Once you complete San Francisco, you'll receive three achievements.
After San Francisco, you don't need to worry about bonus items anymore, you only need to worry about the required items. Complete New York and Hollywood, and at the end of Hollywood you will be given a bonus map requiring you find eight of the same item. When you find all of them, the criminal is caught and you get an achievement.
Complete Beijing, London, and Moscow, only worrying about the required items. You'll get a bonus map at the end of Moscow. Do not use any hints.
Next is Barcelona, Tokyo, and Paris, and then the bonus map at the end of Paris. Remember, no hints.
The final two cities are Rome and Cairo, but each city has four locations and then a bonus map before the story is completed. Still can't use any hints.
When you complete the story, if you used no hints, you'll get the following achievement. If you accidentally used a hint in a city location, go back and do the entire mission over again, not just the city location. If you happened to forget where you might have used a hint, you'll need to start over, which will be an annoyance.
This is where things get complicated. You need to receive the rank of Elite on any mission. Getting elite on a mission is very hard, and you'll need to use a lot of memorization to get the required score. You need to find all eight objects in each area and all three bonus items in each location very quickly to get the score. You're also going to need a second controller, because that heavily boosts your score. Plug your second controller in and start multiplayer. You can then set your second controller down and leave it there, focusing only on your primary controller.
Begin the mission in San Francisco, and go through practice runs. Each location is going to have several possibilities for which eight objects you need to find, but the objects will always be in the same place. Go through practice runs and memorize where everything is. The following pictures show examples of where items are and what they look like, but you'll need to memorize the locations and not rely too much on the pictures here. There are multiple locations for the bonus items, and there are other required items not in the example pictures, but this will give you a good start.
Lombard Street
Fisherman's Wharf
Union Square
At the end of the mission you'll see a score. It doesn't exactly tell you how many points you need for the rank, but you're going to need close to 23,000 points. Aim for above this number and you'll be safe. Just keep trying and eventually you'll go fast enough for the achievement.
The final achievement is currently glitched, and the low status of the game doesn't make it likely the glitch will be fixed. You'll have the opportunity to play two bonus missions. Play the first one, and you can take your time finding all the objects. Once more don't use any hints, and no matter the time you take you'll be considered under thirty seconds.
Wham, Bam…Completed a City Location in less than 30 seconds
Congrats on the 200 GS!