Final Fantasy XIII begins in the floating city of Cocoon, which is located high above the wild world of Pulse. It is the only human civilization that the inhabitants of Cocoon are aware of and was created by a member of a bio-mechanical race of god-like creatures called the fal'Cie, who rarely trouble themselves with human affairs. The exception is the l'Cie, who are humans marked by the fal'Cie for a specific purpose, known as a Focus. These l'Cie are branded with a special mark and granted special powers, but this is also a death sentence because completing the Focus permanently turns the l'Cie into a crystal. Failing to complete the Focus turns him or her into a monster called a Cie Corpse.

Cocoon is run by a theocratic government known as Sanctum, who control the city with an iron fist and considers the l'Cie enemies of the government. The story opens when a fal'Cie marks a woman named Serah as a l'Cie, causing her sister Lightning and fiancé Snow to attempt to rescue her from her fate. Through an unfortunate series of events, Serah completes her Focus and is turned to crystal, while Lightning, Snow, and a small group of others are turned into l'Cie. Now the group finds itself on the run from the government and seemingly doomed by the l'Cie mark on their bodies.

Dungeon exploration in FF 13 is very straightforward. Unlike many of the earlier games in the series, there are no random encounters. Instead, enemies wander the screen and you must touch them to initiate combat. You can try to run past enemies to avoid fights, or you can try to sneak up behind the enemies, which gives you a preemptive attack. It's not possible to run away from battles in FF 13, so it is very important to determine whether or not you want to attack enemies before combat begins. This isn't too important early on, when enemies can almost always be easily defeated, but in later areas of the game, attacking an enemy for whom you're unprepared is equal to suicide.

Fortunately, dying in combat gives you a chance to restart from a nearby checkpoint, so you won't lose hours of progress by accidentally attacking the wrong foe. You can also use certain items, like smoke bombs, to stun enemies or sneak past them. If you feel particularly clever, you can even use smoke bombs to sneak behind an enemy and get an automatic preemptive attack, which is a great way to open up fights against tough opponents.

FF 13's leveling system is a bit different from the traditional method of gaining experience and leveling up. If anything, it is far easier to describe it as the Final Fantasy X Sphere Grid mixed with the Final Fantasy X-2 Job system. After the characters become l'Cie, they gain the ability to power up themselves using the Crystarium system.

There are six jobs that a player can take in battle: Commando, Medic, Ravager, Saboteur, Sentinel and Synergist. A commando is a physical fighter, focused on dealing non-elemental damage, and a medic is based on healing. A ravager is a ranged attacker who uses elemental magic spells, and a sentinel is a tank who draws enemy aggro and defends against enemy attacks. A synergist is a support character who buffs allies, and a saboteur focuses on debuffing enemies. Each of these jobs is called a role and has a unique place in combat. Instead of leveling up your characters traditionally, you level up their roles using Crystal Points, which are earned at the end of combat.

Each role is set up rather like a board game, with a series of interconnecting spheres making up the Crystarium. In order to travel between each sphere, you have to spend a certain amount of Crystal Points. When you reach the next sphere, your character is given a bonus, either in the form of a status increase or a new ability, and status increases apply to all roles. If you level up the commando role heavily, then your hit point and magic bonuses will apply to all roles for that character.

Skills, on the other hand, are unique to each role. If your character isn't in a synergist role, he can't use buffing spells, and if he's not in a medic role, he can't heal. Every Crystarium is straightforward to level. There are branching paths, but these branches are more like side trips instead of actual variations. You can step off the main path for a bit to gain additional skills or stat upgrades, but you'll always be traveling along a set path.

While there are six roles, not every character has the same Crystarium in the same role. For example, Hope and Sazh both begin with the synergist role. Hope's version of the Crystarium focuses mainly on defensive spells, like Protect and Shell, whereas Sazh's focuses on offensive spells, such as the all-important Haste or changing the elemental damage a character deals. They may both be synergists, but they serve very different roles in combat.

The Crystarium is significantly more limited than FF 13's Sphere Grid. To begin with, each character has three roles in which he or she specializes. For example, Lightning is a commando, medic and ravager, while Fang is a commando, saboteur and sentinel. For the first 20 hours of the game, your characters are only going to have access to those roles. Once you unlock the ability for a character to use every role, you're going to have to pay significantly to use the roles outside of a character's specialization. A high-level stat increase in a specialized Crystarium can cost upwards of 4,000 CP, but that same level increase in a non-specialized Crystarium can cost 18,000 CP. It's possible to make a character a jack of all trades, but you'll have to do some exceptional grinding to pull it off.

The second — and likely more controversial — limitation is that your Crystaria are limited by the plot. Early on, you can only reach low-levels of Crystarium, and even if you have enough CP, the higher tiers are locked to you until you defeat a boss. Each major boss you defeat unlocks another level of the Crystarium, which allows you to level up further. This effectively means that it is impossible to power-level for most of the game in FF 13, but if you can reach the maximum Crystarium for a particular point of the game, you're more than capable of dealing with anything in battle.

The various roles that you take in FF 13 are the focus of the new and very unusual combat system. It may be overwhelming to some gamers because battles are so different, mainly due to borrowing more from Atlus' Persona games than anything in the rest of the franchise. Battles are now an unusual mix of real-time and turn-based combat. Players control only the leader of the party, and the other two team members are AI-controlled and can't be selected. The MP system found in most other Final Fantasy games has been replaced by a new version of the Active Time Battle system. Your main character has an ATB bar that fills up very quickly during combat, and every action the character takes — whether it's attacking, magic spells or defending — takes up a chunk of this bar. The longer you wait, the more bar you'll have access to, and the more actions you can take at once.

Combat takes place in real time, though, so while you're waiting for the bar to fill, your enemies are taking actions and moving around the battlefield. Sometimes it is more effective to use a smaller bar in order to take a quick action, instead of waiting to use a full bar every time. This effectively means that you have infinite MP to use; healing, debuffing, buffing, attacking, defending, and almost everything else in the game are governed by this ATB system. Before you think that this makes things too easy, be aware that the game has more than compensated for the increased ease: Enemies hit harder and faster than any other game in the series.

As mentioned above, your partners are AI-controlled, and this is where the Paradigm system comes in to play. Your characters have the aforementioned roles that they can take in combat, and these roles are paired together into paradigms. Each paradigm is comprised of three roles, and you can switch between the roles at will. For example, you can use a Commando/Ravager/Medic to attack enemies while staying alive and then switch to Commando/Ravager/Ravager for an all-out assault at the touch of a button. Switching paradigms alters your available abilities and your partner's AI patterns, so if you want to stay alive, you need to know when to switch paradigms. Pulling out a sentinel before a big attack or a saboteur during a lull in the combat is a key to defeating enemies.

For those who have memories of the sometimes-incompetent AI in Persona 3, there is no need to fear. FF 13's AI is easily the most effective I've ever seen. It is so effective that it sometimes makes the players feel out of place. The AI knows exactly what to do in every situation. If an enemy has an elemental weakness, it'll strike it, and if someone needs to be healed, the medic knows exactly who to heal. The synergist will buff characters in exactly the right order for every fight, and the defender knows exactly when to taunt and draw aggro and when to defend.

The AI also learns as you learn about enemies. Each enemy in the game begins as a blank slate, but as you learn about their strengths and weaknesses through combat, it will be recorded. You can check strengths and weaknesses at any time, but the AI learns them as you do. An AI Ravager may begin a battle by casting blizzard, fire and thunder and Blizzard spells to determine an enemy weakness, but once it does, it'll begin exploiting that weak spot. In many cases, they're more effective than human players could ever be, and the challenge comes from proper paradigm switching, not your attack selections. The AI can only function as the role it's set as, so if players are not intelligent about switching roles, they'll find themselves being overwhelmed because they lack a sentinel or unable to stay alive due to the lack of a medic.

In order to be victorious in combat, you must also pay attention to the break system. Every enemy in the game has a Break meter, which is filled by attacks from ravagers. The meter drains just as quickly as it fills, though, so in order to keep it steady, you must use a commando. Every attack from a commando will cause the Break meter to fill up to the point that the ravagers had it. To best fill the meter, you must use repeated quick attacks to prevent them from interrupting your attack chain and their Break meter from draining.

Once the meter is full, enemies go into Break state, which means that enemies take a lot more damage from your attacks. In addition, broken enemies can be knocked into the air by a commando; this allows you to juggle them in the air for more damage, and this also means you're taking away their chance to counterattack. As if that weren't enough, enemies lose a ton of their resistance to status effects when broken, allowing a saboteur to hit them with all kinds of debuffs, including ones that normally fail. To best defeat an enemy, you must break them, as many enemies are too durable to kill with regular attacks. It may sound simple enough, but enemies go out of their way to break your combo chains and drain their Break meters. They may knock over characters or attack so fiercely that you need to dedicate one of your party members to a sentinel or medic role just to stay alive. Managing your paradigm shifting so that you are always keeping the meter full is the key to success in combat. The Break state only lasts briefly, but if you exploit it, you can even defeat difficult enemies with relative ease.

While there is no MP in FF 13, there are Tactical Points, which are used for very rare spells and can significantly alter the tide of combat. For example, Libra allows you to quickly see part of an enemy's stats; this is very useful against bosses or strong enemies, as your ravagers and synergists will be instantly able to exploit enemy weaknesses instead of guessing at them. Unlike regular spells, TP doesn't regenerate during battle; you earn a small amount of TP after each skirmish, and you can hold up to five TP at once. You should only use TP when you need to, since regenerating it takes time. There are certain items that can be used to regenerate TP, but they're rare enough that they should be saved for emergencies and not squandered on weak enemies.

The most notable of these Tactical abilities are summons. One of the benefits of being l'Cie is that each character also gains a summon monster, which are exclusive to the character. Each character earns a summon monster over the course of the story, after which he or she can call it into battle for a whopping three TP. A summon will replace the other two characters in battle and begin fighting on its own. Fighting alongside a summon builds up its Gestalt meter, and once you have filled it, you can press the Square button to activate Gestalt Mode to transform the summon into another form that the summoner controls. Lightning's Odin, for example, turns into a horse and his Zantetsuken sword turns into two blades for Lighting to wield while riding the horse.

Once in Gestalt Mode, players have access to a series of attacks, which are performed by certain button combinations. Each attack takes a certain amount of points from your Gestalt meter, or you can choose to use all the remaining points to perform a ridiculously powerful finishing attack. Once all the points are spent, the summon monster vanishes. In addition to being very powerful, the summons have a secondary benefit: They'll instantly heal the main character and revive any downed characters when they leave. This makes them a very useful panic button during combat. The downside, however, is that if your main character is defeated before he activates Gestalt Mode, you'll lose the summon monster's most powerful attacks, although the main character will be revived as it leaves.

Every battle is graded after you finish the fight. Depending on how quickly you killed the enemies and how good of a job you did at breaking them, you'll earn up to five stars. The more stars you receive, the better of a chance you'll have of scoring rare loot drops. If you want to make sure you have awesome items, you'll want to beat enemies as quickly and efficiently as possible. It's perfectly easy to win fights by playing ridiculously defensively and using an attacker to chink away at enemy health, but you'll be graded poorly for it, and it's also very boring. One interesting feature about FF 13 is that the end of combat means your party is fully healed. This may sound like it makes the game too easy, but considering that you have roughly infinite healing spells available, it only makes sense. It also means that every fight in the game assumes that you're going in at full health, and enemies are not afraid to take advantage of this by opening with powerful attacks.

FF 13 is considerably more linear than the last game in the franchise, so it is far easier to compare it to Final Fantasy X in that regard. As the players are l'Cie on the run from the government, they can't really take the time to visit stores or go on side-quests. Most of your shopping is done through stores located at save points. You can use money to buy items, weapons and materials from these shops, but don't expect it to be easy because enemies don't drop money. You can only get cash by selling enemy-dropped loot, so money is very tight, but you also have a lot less to spend it on. The after-battle healing means that potions and phoenix down are used only in combat, so you'll primarily be spending money on materials for synthesis. Each character has a small handful of weapons and accessories he or she can find. Rather than buying new weapons in every town, you have to power up any weapons you find by using synthesis. Melding different materials to a weapon can give it different amounts of experience. This experience levels up the weapon like a traditional RPG character and also increases its abilities and stats. Certain materials can even change the weapon into other, more powerful weapons with special abilities. Depending on how you level your weapon, you may even create similar weapons with different special abilities or stats.

The game's linearity breaks up a bit once you reach Gran Pulse, which is an area in the later stages of the game. Gran Pulse is very different from Cocoon; it's a wild land and even though monsters exist in Cocoon, they're nothing like the Gran Pulse monsters, who are gigantic and deadly. While you can advance the plot in Gran Pulse, you're also able to take missions from Cie monuments. These missions make up the bulk of the title's side-quests and usually involve defeating some of the most powerful enemies in the game. You can finish the game without doing most of these side-quests, but you'll miss out on fun fights and rare materials by doing so. There are even rideable Pulse Chocobo that you can find so that it's easier to get around. It's an unusual way to structure a game, and it is likely to be one of FF 13's most controversial aspects.

Final Fantasy XIII is a fairly different game from its predecessor. In many ways, it is the opposite of Final Fantasy 12. It is far more linear and story-focused, with a greater emphasis on the characters than the world around them, but the real differences are in the unusual combat system and game mechanics. Borrowing heavily from games like Persona 3, FF 13's battle system is unlike anything else in the franchise. It is fast-paced, frantic and exciting, introducing a surprising amount of speed and twitch gameplay into what is otherwise a turn-based combat system. It's one of the most visually interesting and exciting combat systems that the franchise has had, and each fight feels intense. The Crystarium system keeps the characters unique and interesting without pigeonholing them into specific roles, and it also allows for some customization between the different paradigms. FF 13 is an unusual game and takes a lot of getting used to, but RPGs fans who enjoy interesting combat systems will find a lot to like. FF 13 comes out in the U.S. and Europe in March 2010 for both the PlayStation 3 and Xbox 360.