Uncharted 2: Among Thieves is an action-adventure game, with robust shooting, platforming and puzzle-solving elements. Unlike some "sandbox" action-adventures, where you're let loose in a large world and it's up to you to find out where to go next and what do to, Among Thieves is played linearly, with 26 chapters all going in order. Within each chapter you will have a linear path to the end, though that's not to say it will always be obvious how to proceed. There are no unnatural barriers to exploration, such as invisible walls or running into the side of the screen. Rather you may find the way back blocked by having to jump down farther than you can jump up, or you'll move to a different area in a cut scene.
The story of the game involves searching for an elusive treasure, and your goals shift as you learn more about it. The main thrust of the game is to get from point A to point B, sometimes alone and sometimes with one or more friends. The game has an autosave feature, which requires that you choose a save slot before you start. There are also unobtrusive checkpoints, where you will resurrect if you die, so you won't have to start a level completely over if you get very far into it. The main gameplay elements are combat, platforming, puzzle-solving and treasure hunting.
In combat you often have the choice between a direct approach and a stealthy one, although one or the other may be forced on you at different times. The game proceeds from area to area, and though you won't explicitly be shown when you've moved from one to the other, you'll note the transition by moving over large distances, a cut scene or a period of platforming rather than fighting. After you've cleared out an area, make sure to go around collecting weapons and ammunition before moving on.
When taking damage, you'll see red around the perimeter of the screen, with more blood meaning more damage. The side of the screen on which it appears indicates the direction of attack, in the case that someone is shooting at you. When you get very low on health, the screen goes gray and you can hear your heartbeat. Drake recovers quickly if he's not taking any more damage, so find a safe spot and wait for the screen to clear if you're afraid you're about to die.
Alerting enemies to your presence in one area immediately affects the enemy AI of all others in the area, but doesn't affect any other area, even in the same chapter. The only ways to break your stealth are to be seen by an enemy or to fire a weapon. Noise from running around, climbing, loading your weapon, etc. has no effect and in most cases, enemies won't notice a dead comrade on the ground. An added benefit of using stealthy take downs is you will be rewarded with extra weaponry or ammunition. This will be noted by a blue ninja icon by the normal ammo/weapon pickup icon. Being spotted may also cause more enemies to swarm the area than would have if you were able to stealth kill everyone.
There are two types of stealth attacks: free attacks where you come up behind an enemy, and stealthing from cover, where you are behind cover or you're hanging below the enemy. Stealthing from cover has the benefit of returning you to a covered position after performing the attack, while normal stealth attacks allow you to take out moving enemies. You can be extremely close to other enemies while stealthing someone, as long as you're behind them. In the case of hanging below an enemy, it is still effective, even when the enemy is aware of you (you can still grab them and pull them over the edge to their deaths). When you're behind cover and an enemy approaches around it, Drake will give a visual clue that he is ready to attack by slightly adjusting his position. Wait for this cue, as jumping out of cover right in front of an enemy will have a detrimental effect on your ability to continue unnoticed in the area.
When stealthing enemies is not an option, or your cover is blown, you'll need to rely on your weaponry and any objects in the environment to take out the opposition. You'll have a large selection of weapons throughout the game, and certain ones will be more effective than others, depending on the situation and the enemy. The biggest key to victory is proper utilization of Uncharted 2's cover system. By pressing behind nearly any large object with a flat vertical section, Drake will take cover behind it. This will protect you from enemy fire coming from the other side, and allows you to move from your current position without being seen to trick the bad guys. When behind cover, you can blind fire with , which will cause you to simply stick your gun around the corner or over the top of your cover and fire away. You can aim after a fashion, as a loose reticle does appear, but the camera stays in the third-person perspective and doesn't zoom in.
Alternatively, you can use to aim, in which case Drake will pop his upper body out from cover and you can fire normally with more protection. Get used to where the weapons will be pointing when you go into aim mode so you can adjust the camera before breaking cover. The less time it takes you to acquire the target while aiming, the better. Note that aiming from cover can result in you being spotted if you were still being stealthy, so if you're about to begin a firefight, take your first shots quickly to have the element of surprise. When cover provides room to move, you should do so, as the enemy watches the place from which you last attacked. Even aiming around the other side of a pillar will be helpful. In some cases, if you can move from cover to cover quickly enough, the enemy won't see you at all and you'll be able to outflank them.
The final key to being successful in a shootout, is to prioritize your enemies. Depending on the situation, you may want to take out either the toughest enemy, the one with the longest range to their weapon or the one with the strongest weapon first. Enemies with explosive weaponry, such as RPG - 7s or M32 - Hammers, need to be dealt with immediately. For groups of enemies, consider using a grenade or propane tank to take them out. Any explosives you have are great to use against groups, machine gun emplacements and enemies using the riot shield.
Even on mainly combat chapters, there will always be something to climb or jump across. There is a ton of platforming in the game, and it includes scaling walls, swinging on ropes, jumping large distance, and much more. Climbing somewhere is the likely way you'll move to another area. To climb something, just run up to it and press while pushing in the direction of the object. Once you're hanging onto something, you can either climb in a direction with , jump to another handhold or ledge with , drop down with or shoot your handgun by aiming first with . At the top of thin climbable objects, such as signs and billboards, press without specifying a direction to hop over to the other side. It's not always obvious what can and cannot be climbed, so when in doubt just try it. The same goes for what you can jump to. In addition to using to go up, you can also use at the edge of platforms and roofs to hang over the side.
Some climbable objects require you to swing from them to proceed. These can be ropes and chains changing down vertically, and poles sticking out of walls or across gaps horizontally. Some ropes are hanging down by themselves, with nothing surrounding them. Jump out to these and use to direct the motion of your swing. For a big change of direction, let Drake come to a rest, then position the camera where you can swing in the direction you want to go. For ropes that are hanging down the sides of walls, when you jump to them you may need to wall run before jumping off. Simply run back and forth on the wall to build up your speed, then jump at the end of the arc. Horizontal poles can be climbed back and forth on, or you can press in the direction you're facing, and Drake will start swinging. Press at the height of the swing to jump forward.
There are two types of puzzle-solving in the game: situational puzzles where you work out what you need to do by clues in the environment, and journal puzzles that require information collected in Drake's journal. The first type of puzzle is found throughout the game and may be as simple as figuring out what you're supposed to climb to get where you're going and some can be figuring out large, complex mechanisms over huge areas. Pay attention to what your companions or even Drake have to say, as they often drop little clues about what to do next. If tips are on (enabled by default in the Options menu), you may be prompted by the game either by notifying you there is a hint available by pressing , or simply telling you what do next with text at the bottom of the screen. These are usually dependent on how long you've spent in an area without performing the expected actions.
Some puzzles can't be solved by environmental cues alone. In those cases an icon pops up in the lower left hand corner of the screen indicating you should press to view the journal. Drake stores the information he collects along the way in the journal, and you'll often see object and even full pages from cut scenes represented in the journal. For these puzzles, you'll have to match what you see in the journal with what's going on in the game. For instance, you might look for symbols found on the walls in game in the journal.
Littered throughout the game are various treasures. These can be noted by the shining, white glow they give off. Treasures can be found on the ground, up in places you'll need to climb to, or at inaccessible spots where they must be shot down. Some treasures, especially early on, can be found fairly easily as you move naturally through an environment. Most, however, are hidden in out of the way places that require some searching. Common places to find hidden treasures are on the opposite sides of objects and structures that you would normally pass without looking back at, up on walls and ceilings, and farther along routes than the obvious place where you would turn off to another area. In addition to picking up treasure while standing on the ground, you can also grab them while hanging from a ledge or even while swinging from ropes. There are 101 treasures found in the game, and by collecting more of them you will earn medals and trophies.