- Note: This walkthrough assumes that you're immediately familiar with the controls and terminology for this game.
The game opens with an FMV sequence, before granting you control of the main character, Cloud Strife. Search either both of the felled soldier's bodies, or search one twice, for a maximum of two Potions. Make your way to the exit at the furthest end of the screen, and the game throws you straight into a (relatively easy) fight.
Cloud, for the moment, has access to two Magic spells; Bolt and Ice. Don't use these yet, as the enemies here aren't strong enough to warrant using them. You'll soon get another member to add to your party, Barret Wallace, who has no magic equipped, and who has a long-range weapon equipped. As soon as you're able to, switch Barret to the back row to minimize the damage he takes from physical attacks; as he has a long-range weapon, he'll still do full damage with his weapon for physical attacks while in the back row.
Once you're in the main complex, speak with Biggs and Jessie to open the doors for you. While you're here, there is a Phoenix Down that can be looted from a chest in the room to the south. Speak to Jessie again to open the elevator door. Head into the elevator, and press the button on the right. Once at your destination, make your way down the structure, and enter the door on the bottom left. Follow Jessie, and talk to her for a brief explanation on how ladders work. The blue object glistening in the light is a Potion. Grab it, and make your way down the pipes. There is a Save Point here, and it is recommended that you use it.
Move to the bottom of the screen, and pick up the Restore Materia. Go to the reactor at the top of the screen, and Cloud will set the bomb. An alarm klaxon will sound, and you will encounter the first boss of the game: the Guard Scorpion.
Have Cloud use Bolt repeatedly, as this boss is vulnerable against Lightning damage, and both characters should use their Braver and Big Shot Limit Breaks when available. Do not attack the boss while it has it's tail raised in the air; this will cause it to unleash a devastating counter-attack.
With the boss dispatched, you have ten minutes to evacuate the building. Go back the way you came, stopping to free Jessie, who has trapped her foot in the scaffolding. Retrace your steps back up to the elevator; once back in the first series of rooms, talk to Jessie and Biggs again to open the doors to the exit. As you run toward the exit, the party joins you, and the evacuation completes with a spectacular FMV.