This first playable section of the game functions similar to a tutorial.
Final Fantasy XII begins in the Nalbina Fortress. You start off the game in control of a character named Reks. Reks is not the main protagonist of the story, but rather a temporary character that you control as part of the introduction to the game. This introductory chapter gives you an overview of some of the basic controls and some of the fundamentals of the battle system.
Start off by rotating the [Right Control Stick] as instructed by Basch. Use it to circle the viewing angle around Reks once. Use the [Left Control Stick] as instructed to walk up to and stand in front of Basch. He will give you a brief overview of how Talk Icons work. Walk over to the Dalmascan soldier and press the [X Button] to speak with him.
Make your way up to the gate to initiate another short conversation with Basch about Action Icons. Walk a little bit further towards the Iron Gate and press the [X Button] to open it. Basch will then give you a quick explanation of the Party Menu and the general battle system. The Red Line is a Target Line and it indicates that Reks is being targeted by an enemy combatant. The Blue Lines represent who your character or characters are targeting.
Follow the team across the bridge after the Imperial Swordsman is defeated.
The first boss is designed to be extremely easy. The attacks from the other ally soldiers are enough to take down the boss without your help but you may as well join the fray to speed the battle up. Reks will normally only be hit by Area of Effect (or AoE) attacks, which are attacks that hit multiple party members. You can use Potions by pressing the [X Button] and selecting the Item command if you need to refill Reks’ HP.
Basch’s attacks deal a very high amount of damage and he will eventually end the fight by using one of his special moves once Air Cutter Remora’s HP drops to around 50%. The battle will end automatically at this point.
Four more soldiers will approach from the stairs at the end of the bridge once the battle against Air Cutter Remora has concluded. Defeat all four of them and proceed through the doorway at the top of the stairs and into the Nalbina Fortress.
This is the first time you gain full control of Reks and can actually explore an area of the game (albeit a very limited area of the game). The mini-map in the top-right corner of the screen can be used to help you navigate. You can also press the [Select Button] as explained by Basch to bring up the Map Screen. Your goal is to navigate to the area marked by the large red X on the map. Note though that there are multiple floors shown on the mini-map delineated by brown lines leading between each of the levels.
Basch will also explain to you how to retreat from battle. Press the [R2 Button] to stop your party members from attacking and run from your foes. There is a treasure chest on the right side of the hallway (note that treasure chests in Final Fantasy XII contain random items so this guide will not indicate what item you will receive when opening them). Follow Basch down the hallway and into the room on the right and take the stairs up to the second level.
Continue along the pathway going around the corner to meet up with Basch once more. This time he will talk to Reks about Save Crystals. You can save your progress by approaching a Save Crystal and pressing the [X Button]. Touching a crystal will also fully restore the HP and MP of your party members. There is nothing else to do on this level so continue up the stairs to the Highhall.
As Reks, Basch and the other soldiers make their way up the stairs, a group of Imperial Swordsmen will approach from the rear. Reks will offer to take care of the soldiers while Basch and company continue up the stairs. The Imperial Swordsmen involved in this battle are much weaker than those previously fought. You will likely have to use either a Potion or a Cure spell at some point during this fight.
Defeat the three Imperial Swordsman and then follow Basch down the pathway. Go through the Passage Doorway and approach the huge double-doors at the end of the pathway to initiate the next cutscene. Reks will stumble across King Raminas and all of the men. Basch will appear revealing that it was he who killed the King and will then stab Reks with a small dagger. The last thing Reks will see is the enemy capturing Basch.
This is the end of the introductory chapter. After a short interlude, the next chapter begins in Rabanastre.