The birth of an underrated franchise.
You play the role of Sly Cooper, a master thief raccoon. As the story is told, his parents were killed by a group of thieves called the Fiendish Five when he was a kid. Now as an adult, he seeks out the Fiendish Five to reclaim his birth right: a book named "The Thievius Raccoonus." Of course, he's not coming alone in this. You're joined by your friends: Bentley, a turtle with a high IQ and the person who tells you the 411 on your missions whereas Murray, a hippo, acts as the muscle and second character for certain missions and Carmelita Fox, a police constable who will be on Sly's tail throughout the whole game.
The first Sly Cooper plays like a traditional 3D platformer: use the left analog stick to move Sly, right analog stick to move the camera, square to attack, X to jump; that kind of thing. Though, despite being a platformer at heart, it requires a bit of stealth as well. As a master thief, the members of the Fiendish Five don't take kindly to you stealing stuff on their turf so you'll have to deal with various laser security systems and spotlights scattered around the levels. It's not complete necessary to be stealthy, but in the later levels it is.
Anyone familiar with Super Mario 64 will automatically know how the presentation of Sly Cooper. Each world you enter is a major hub with levels scattered throughout, only this time around you are hunting for treasure keys. The objective of each level is to locate treasure keys belonging to the specific Fiendish Five member to unlock further levels and more keys to find in order to battle them for a piece of the Thievius Raccoonus. Each boss fight is rather unique and quite fun, depending on who you are up against.
In regards to the levels, a lot of them are the typical 3D platforming sequences and on occasions they would throw other types of missions to prevent it from being boring. Some require you to collect treasure chests from under the sea in a specific set of time and on some occasions, Murray is essential to getting the keys. You may have to take control of the Cooper Van (yes, the Cooper Gang has a van) to race enemies or protect him from a turret as he makes a mad dash for the key. It does mix the levels up pretty good to prevent boredom in such a good game. Oh, and remember Carmelita? You better. Some missions involves her shooting at you and avoiding her line of fire along the way.
Don't think that this game is a cakewalk, because it's not. While it's not extremely difficult, it's still the more difficult game in the series so far. Take a single hit by anybody or anything, you're dead. Lose all of your lives in a level or at a boss, start all over again. It can easily be avoided by collecting coins and lucky horseshoes along the way to be able to take more hits before dying. Collecting 100 coins earns you a blue horseshoe, 100 more earns you a gold one and continuing to collect coins and horseshoes will also earn you more extra lives along the way. Also to keep you at ease are special upgrades hidden in secret vaults that can only be opened if you collect clue bottles. They range from 20 to 40 bottles in EACH platforming level and collecting them all earns you access to the vault with various upgrades from immunity to water, fake Coopers to trick enemies into attacking, coin magnets and etc. It's not necessary to collect the bottles, though the contents are useful in certain levels.
The Sly series is also known for its humor. While it was better in Sly 2 than the others, it's actually pretty good. Murray's antics will definitely have you laughing and the dialogue Sly has with the Fiendish Five (with the exception of the last one) are worth a chuckle or two.
It was a fairly good start to the Sly series. As difficult as the game could be, it's not so hard once you get use to being stealthy and understanding enemy movements. The controls work well, it is fair with its checkpoints and all in all, a fun game.