Dirge of Cerberus: Final Fantasy VII/Chapter 1 - Sea of Flames

Part One
After the opening FMVs get ready to fire. There are three Deepground soldiers infront of you and they're probably already firing at you - so shoot them off. Continue to pick up the potion, then climb the ladder. There are 2 more Deepground enemies further on, so blast them away. One of them even leaves you some handgun bullets (36 of them). Take a right at the split then destroy the crate for 500 Gil then turn around and go left at the junction. Now, to the west of you is a bunch of soldiers conveniently around a barrel. The barrel contains explosive material - so rather than aim for them and risk getting hurt as you pick them off, make sure you're a resonable distance away and shoot the barrel. The northwest dead end yeilds a potion.

Go back and make your way down the staircase, there are 3 Deepground soldiers that block your way down, so neutralise them. A mission comes up, 'Protect the Civilians!', so protect them by gunning down the soldiers that are after them. Further details of the mission are provided in the 'missions' section below.

Progress north for a few potions, and in the southern part is a boy that needs saving. Return to the main path and next turn right to gain the Fire Materia and a short tutorial on how to use it (equip it, press L1 to aim it, then L1 again to release magic), there's also a mako point to charge up your magic.

Continue onwards, and when you see the laser gate (blue lasers blocking a certain path), examine it, then look behind you as a Deepground soldier will be spawning. Kill her to get the key card, then use it on the gate.

Blast your way along, and make sure you pick up the Limit Breaker one of the first guards drop when he is disposed of. At a certain point you'll see a cutscene, and so you have to save another citizen (Mission: 'Save the Abducted Girl!'. To do this, take out all the surrounding soldiers, there's also a few snipers on the second floor windows.  Open the container by going up to it and pressing 'X' and kill the dog within.  There are also a few item cases around, which contain a hi-potion, a phoenix down and a potion.

After the touching reunion between mother and child, go back to the main path and continue west to get the Sniper Scope, then turn into the other alley. Annihilate all the soldiers to get the next Card Key and head to the next laser gate to unlock it. There are more enemies here to destroy, do so and proceed to the top floor to get the phoenix down and 180 handgun bullets. Then go back downstairs to find another 4 soldiers, so dispatch them, and make sure you get the Long Barrel, which one of them drops. Get the hi-potion and the bullets from the cases, then leave for the sub-boss fight.

Sub-Boss: Dragonfly
Make sure that the Long Barrel and your Fire Materia are equipped and blast away! Just make sure that the buildings don't get in the way. Avoid the missiles by dodging and jumping. There are mako points and boxes that if broken, contain weapons and restorative items, so use them if you have to. Once you've damaged the Dragonfly enough, a bunch of soldiers come out to try and spoil the fun, so kill them off.

Missions
Note: In each chapter of Dirge of Cerberus there are missions that are (almost) entirely optional, but if you want more gil at the end of each chapter you have to at least half-do the mission. In other words, the more missions you do and the more enemies you kill, the more gil you get at the end of the chapter.

Protect the Civilians!

 * Defend the civilians from the Deepground soldiers.
 * There are a total of 25 civilians.

Save the Abducted Girl!

 * Open up the crate the girl is imprisoned in and kill all of the surrounding enemies, the girl will then be saved.
 * The door will take time to open, so don't bother standing there to wait for it as there are enemies spawning nearby - including a sniper on the second floor of one of the buildings, so kill the enemies while waiting for the door to open. The girl won't be harmed while you're fighting the enemies, so don't bother guarding the crate.
 * This mission is (possibly) mandatory.

Locate the Cardkeys

 * Get all 5 cardkeys that are in the chapter.
 * In the Japanese version there are only 4 cardkeys.

Assist the WRO

 * From the middle of the chapter 12 members of the WRO will fight with you.
 * The WRO troops are subject to an inverse form of the stormtrooper effect - allegedly elite, but easily killed due to their limited HP.
 * Therefore, the more WRO members that make it out alive, the more gil you get.