This isn't a Metal Gear game, so you won't find stuff like rocket launchers or katanas here. These tools are all about stealth.
Gadgets
The stuff Sam needs to get around.
Lock Picks
They say that locks only keep out the honest citizen. Well, Sam is not exactly an honest citizen. Feel free to break out your tension wrench and pick set and become your own master key.
To use the lock picks, select them in your inventory and press the Fire button while standing next to a locked door. Use the left stick (or movement keys) and rotate it slowly until you see/feel the lock vibrate. This means that you're pointing at the proper "quadrant" of the lock. Wiggle the stick in that quadrant until that part of the lock is picked. Repeat the process as many times as necessary until the lock is freed and the door is unlocked.
In the Gamecube version (and presumably the PS2 version), you don't need to select the lockpicks - instead, there is an option in the use menu that automatically uses them.
Disposable Lock Picks
Tiny explosive charges that are designed to open a lock as quickly as possible by destroying it from within. They make a bit of noise though, so be really careful.
Optic Cable
Use this to see underneath closed doors before opening them. Very handy to check if somebody's inside a room before you barge in.
Laser Microphone
A special type of microphone designed to eavesdrop from a distance. It works by shining an infrared laser beam at a window and detecting minute vibrations that result from sounds from inside the window (for example, people talking on the phone or in a glass elevator). You'll use the laser mic a few times throughout the game.
Camera Jammer
Point this thing at a camera and it will not be able to see you.
Items
Simple everyday objects that Sam can use.
Medical Kit
Heals about a quarter of your health bar when used.
Frag Grenade
Pull the pin, and toss it. Makes quite a bit of noise, so you should only use it in an emergency.
Wall Mines
Wall mines are very dangerous. When you stick them to a wall, they make beeping noises - you had best run away before the mine is armed. To disarm a mine, move VERY SLOWLY toward it and press the Use button. Pan the camera so that you can see the flashing light, and when it's green, press the Use button again to disarm it safely. If you screwed up, the mine will beep faster until it finally explodes. You have a small window to run away before it does.
Weapons
Fabrique Nationale Five-SeveN Handgun
Sam's main sidearm throughout the game. A simple little pistol with an attached suppressor. It's not very powerful, so it might take a couple shots to kill the average guard with it - and once you get the SC-20K system, this will only be really handy to shoot out lights, windows, and other things. Holds 20 rounds per clip. You can carry a maximum of 40 rounds.
SC-20K Modular Assault Weapon System
The SC-20K (actually a modified FN F2000 rifle) is a bullup-style assault rifle with an attached sound/flash suppressor, a 4x scope, and an underslung utility launcher. It's capable of full-auto and semi-auto fire, holds 30 rounds per clip (with a maximum of 60 rounds), and also doubles as a sniper weapon. The utility launcher can shoot all kinds of stuff - ring airfoil rounds, cameras, you name it.
Sticky Shockers
A special type of ammo that, upon attaching to a surface (ideally, an enemy guard), will unleash several volts worth of electricity, stunning and knocking out its target. The charge is only good for one shot, after which the shocker mysteriously disappears. Part of the SC-20K.
Ring Airfoil Rounds
Aerodynamic "ring" rounds that, when shot from the SC-20K's utility launcher, will fly at outrageously fast speeds until they make contact with a target. Hitting an enemy in the head with one of these means an instant knock-out. Hitting any other part of their body will simply daze them for a few moments, giving you ample opportunity to run up to them and grab them (or finish the job with another shot).
Sticky Camera
A camera that can adhere to almost any surface. Upon being launched, the viewpoint switches to that of the camera. You can pan it around and zoom the view, until you exit the camera view, at which point the camera switches off. You can pick the camera back up, if it's within reach.
Sticky Bombs (GameCube only)
These bombs can come in quite handy. They're hard to find, but you can stick them to walls and detonate them when a guard passes by. The ensuing blast is about equivalent to a gas bomb - it emits sleeping gas that will knock an enemy out. To use this item, you'll need a Game Boy Advance, a cable to connect it to the GameCube, and a copy of Splinter Cell for the GBA.
