Checklists
Basics
Stealth
This is perhaps the most important thing to understand before going into Assassin's Creed: this is not a stealth game. There are pretenses of stealth built into the design, and if you really want to you can play the game as stealthily as you'd like. However, playing the game as a stealth game makes progression very slow. As you play the game, you'll realize that the pretenses of stealth are very artificial and really have little if any influence on the game.
Assassin's Creed divides player actions into the categories of socially acceptable and socially unacceptable. The actions deemed socially acceptable all are very slow and very limiting. And while you may at first feel that you need to keep a low profile, the truth is that it doesn't matter. Forget the notion of playing Assassin's Creed as a stealth game and you'll enjoy the game a lot more and conquer it more easily.
The consequences of high profile, socially unacceptable actions are very slim. While running around towns, you'll note that citizens and guards will remark at your horseplay. They do not, however, do anything about it, unless the town is on high alert and you do something goofy in front of a guard. If guards are actively seeking for an assassin, a socially unacceptable action will tip them off.However, the other 99% of the time you're playing, socially unacceptable actions have no negative consequence unless you take the snide remarks personally. Note that when in the Kingdom overworld, pretty much all guards are actively seeking assassins. Therefore, galloping on your horse will alert them and they'll start chasing you. Since moving slowly through the overworld is a tedious process, we suggest running anyway. The guards will never catch you if you're on your horse, and you can simply find a hiding spot if you need to reset the social status meter.
Combat
Assassin's Creed's combat system is pretty unique and can be a bit confounding, though when you break it down you'll find that the combat is actually rather simple. There are a couple of simple defensive techniques, a slightly obscure but really quite simple combo system, and the basic ability to grab.
Defense
While locked onto an enemy, press and hold the guard button to assume a defensive stance. While in this stance, most enemy attacks will automatically be parried, resulting in no damage. Some enemies will counter your parry, forcing you to rely on other defensive techniques. Early in the game, you'll unlock a counter attack that you can activate while in the defensive stance (just press attack while holding the defend button). If you time the counter just before an enemy attack lands, you'll reverse the enemy attack and deliver a killing blow.
Offense
When mounting your own offense, you've got just one basic attack button. Rapidly mashing the attack button will result in attack strings that enemies will generally guard against. You can also hold down the attack button longer for different attacks, but these too are generally defended. The best way to attack is to attack with combos, which we must emphasize are different from the aforementioned attack strings. To execute a combo, press the attack button once to initiate an attack. At the very moment that your initial attack connects with the opponent (whether it's a direct hit or a blocked attack), press the attack button a second time. If you time it properly, Altair will follow with a single-hit kill attack that the opponent cannot block. Using the combo is key for getting through opponents that defend a lot.
Grab
The grab is another way to get through opponents' defenses as the grab cannot be blocked. You can simply press the grab button to initiate a grab, but we suggest first stepping into the opponent (by tapping the legs button) before grabbing. Once the grab animation has started, you can use the control stick to direct the follow-up throw. Use the grab to move enemies all on one side of you, as it's difficult to fight when you're surrounded. You can also use the grab to toss enemies off ledges—lead enemies to a high building and give 'em a toss for easy kills.
Mini-Missions
Though there are individual missions to accomplish for each memory block, the bulk of Assassin's Creed play is spent completing various optional objectives, mini-missions. There's a handful of varying mission types, and generally each instance of these mission types plays out exactly like the one before it. Once you know how to complete a mission type, you'll be able to apply that knowledge throughout the game as that same mission type shows up multiple times.
Eavesdrop
Eavesdrop mini-missions are by far the easiest to complete. Simply get within range of the target (but not too close!) and take a seat on a bench between two people. Once you're seated, point the camera at the target and press the lock-on button. Follow by pressing the head button and the camera will zoom in on the target while he or she has a conversation. When the conversation ends, the optional objective is completed.
Pickpocket
Much like eavesdrop mini-missions, pickpocket objectives require you to find the target and lock on while nearby but without being too close. Stand around and wait for the target to complete a conversation and he'll begin walking on a predetermined path. Follow slowly behind the target and note the status of your social awareness logo. The target is often suspicious, which is not a good time to attempt the pickpocket. Instead, wait for the social awareness to cool down to complete unawareness. When you've achieved that, slowly walk up behind the target and press the pickpocket button to complete the mission.
Interrogate
Locate the interrogation target first and, as required in other mini-missions, lock on from a distance. Generally, interrogation targets are first found spouting propaganda or carrying on private conversations. After the target is done talking, he'll begin walking away. Follow the target closely without alarming him and he'll eventually lead you to a secluded place. When you've cornered the target, you need to rough him up a bit. For this, we suggest catching the target by surprise with a grab and then following with punches while he recovers from being tossed. This will generally let you score the required number of hits to trigger the interrogation without having to take any punches from the target.
Save Citizen
You'll find citizens around the city that are being harrassed by the local gooney guards. Simply lock onto the guards and approach them to initiate a fight between you and three or four foes. You can sometimes get in a quick hit before the guards pull out their swords, but once you've got their attention you'll need to rely on your combat skills to get you through the fight. When you've defeated all of the nearby guards, press the lock-on button to talk with the citizen you've saved and to complete the mini-mission.
View Point
Completing view point objectives is generally as simple as climbing a tall building and then pressing the head button. There are, of course, only specific buildings that will operate as view point objectives. Once you've synchronized at the top of one of these tall buildings, other optional objectives will display on your map.