As the manual says, you are not a tank. Garrett is a simple human of flesh and bone, and so is quite squishy behind his weak leather armour. Blades, arrows, and bolts are only too happy to make a home in his warm interior. Getting attacked will often result in immediate death, or at the very least a loss of health, and not to mention alerting more guards to your presence. Charging through the levels, sword drawn, is generally a bad idea. There are a few sneaky exceptions to this rule, however. If you're at the end of a mission then you can run to your final objective, safe in the knowledge that the level will end as soon as you accomplish it. Also, various nonhuman enemies such as spiders, zombies, and burricks, can be rushed past and escaped from if you're desperate.

If they don't know you're there, they can't kill you. They've got even less chance of killing you if you aren't there. There are essentially three things to consider when sneaking around. First and foremost is how visible you are. Crouching will make you less visible. You should be constantly aware of the state of your light gem, and any nearby areas which can put it in the black. The light gem has three basic states, shown by the little coloured light on the right:

• Black: A black light gem is ideal. Guards can walk past you without even getting suspicious, and guards on alert will only spot you if they get close enough to walk into you.
• Yellow: Middle ground. You're strictly visible, but not necessarily noticable. Guards will notice you if they get too close, and suspicious guards will spot you from a little further away.
• Red: You're fully visible and stick out like a sore thief. You might as well be wearing a neon sign saying "LOOK AT ME". If you can see a guard, then they can probably see you too.

The one thing you're missing is a sound gem. Fortunately, you have speakers. Turn the volume up. Enable hardware support in Thief's audio options if your sound card has 3D or EAX capabilities. Keep your ears peeled for any noises you may be making. Listen to your footsteps. Running over marble floors is noisy. Creeping over carpet is not. Remember that guards don't have to be able to see you to hear you. Making noise can alert guards with their back to you, guards in the next room, even guards down the corridor and around the corner. Make very little noise and you'll attract very little attention. Fire arrows make lots of noise.

The final thing to consider is where you are. You can be completely hidden and utterly silent, but a guard is still going to get suspicious if he walks into you. Don't obstruct the path, and always stay a step away from enemies. Hide in corners, behind pillars, or in the rafters. Don't plonk yourself in the middle of a room and wonder why the alarms are going off.

Use the lean keys (default Q and E) to lean around corners and see what's coming without making yourself known. Turn the volume up. Again. Stay still, and listen. Can you hear footsteps? Which direction? Are they approaching or receding? How many people are there? What surface are they walking on? Just listening will help you work out where the enemy is without even having to look for yourself. Stand at doors and listen out for conversation coming from the other side. Wait a while. Listen out for idle sounds; not all guards are walking around. Hearing someone clear their throat RIGHT AROUND THE CORNER is going to save you an embarrassing first meeting. Find another route.

Sometimes, you can't find another route. This is where the risky plays can pay off and causing a diversion may be your only choice. Ideally you want the guards to walk one way while you go the other. The obvious choice here is to use a noisemaker arrow. Firing one down a corridor will cause any guards in earshot to investigate the commotion while you quietly slip off in the opposite direction. Unfortunately this tactic deliberately alerts the guards to something suspicious, so think twice. If the guards find the arrow, they'll know there's a thief around and may set off an alarm. It makes a noise as it flies, so try firing it somewhere they won't find it afterwards. If you haven't got any noisemaker arrows, try another arrow or throwing some junk.

Ah, the blackjack. The weapon of choice against human guards. There are only so many guards on each level, so reducing their numbers is a worthy cause. The blackjack, when applied with force to the head of an unwary guard, will knock them out cold with no noise or blood. The only way it can go wrong is if someone sees it happen or finds their unconscious body, so make sure you carry them away to a dark cupboard afterwards. Blackjacking will work on curious guards as well as unsuspecting ones, so don't be afraid to try it. A curious guard is one who thinks they noticed something, but isn't too sure. They'll typically walk slowly, stopping and peering around for a moment before returning to their posts. It's possible to rush them in this state and take them down before they realise what's going on. Once a guard is alerted, blackjacking will have no effect on them at all.

An alternative to the blackjack is knockout gas, like the sort contained in gas arrows. Gas arrows travel in a straight line, so aim the top of your sight at your target. When the arrow strikes it will release a cloud of gas, knocking out all guards withing a small range. If two guards are talking, you can usually get them both with one arrow. Note that knockout gas will affect everyone, even alert guards, meaning that a gas arrow can be used as a last resort if you mess things up. Again, remember to hide the unconscious bodies. You need to breathe too, so aim away from your face.

Oh, and don't worry about the unconscious guards. They won't wake up on you and they don't count as kills.

You're a thief, not a murderer. Don't kill unless you have to, and even then make sure that you really have to. If you find yourself having to kill a human, then you'd probably be better reloading and trying again. Otherwise, your best offensive weapon depends on what you're trying to offend. The sword is handy for chopping up annoying spiders. Using holy water will let your water arrows put the undead to rest. The fire elementals that litter the later levels can also be extinguished with a single, well-aimed water arrow. Fire arrows are effective against pretty much every other enemy, but remember that they are exceptionally loud.

If in doubt, run like stink. Climb ladders, descend pits, lock doors, and generally get somewhere your enemies can't. Dashing into even the deepest of shadow won't help you if you're being followed, so use initiative. Lose your enemies by running around corners. Throw flash bombs to buy you a few seconds of getaway time. If you're in dire trouble, drop (default R key) a mine or two as you run. They'll arm after you run over them, so they won't hurt you.

Your map is invaluable. Study it and plan your routes. The game is paused whilst on the map screen, so spend some time going over it. Obviously you can't plan an entire mission based only on the map, because you'll have to deal with the unexpected, but you can make a good start. Make use of Garrett's notes and any other information on the maps. Rooms labelled "guard room" or "barracks" are probably best avoided. Store rooms may well contain valuables and other items. Offices are likely to be locked. Large rooms and entrance halls will probably be watched over by multiple guards. A little common sense in interpreting the map goes a long way.

Go for lots of loot. Even if your mission objectives don't require it, get as much as you can. The more valuables you leave a mission with, the more cash you'll have at the next mission's loadout screen. Grabbing those candlesticks might seem like a risky maneuver now, but it will let you buy more water arrows for next time. It's a gamble well worth taking.

Oh, and really finally, SAVE YOUR GAME. Half an hour of excellent sneaking can go up in flames just because you accidentally walked into a guard. Set the quicksave key to something memorable, and try not to confuse it with quickload.