OR How I bit off way more then I can chew.

So after our last campaign ended I asked my players what they wanted to do next as they basically created the D&D equivalent of the multiverse. Their idea was a more modern setting still using D&D,( Because my players don't really like the Adventure books ) So I ( in a moment of insanity) asked Like Final Fantasy, and they thought it would be fun...So I am now trying to adapt the setting and cutting out the story of Final Fantasy 7. Mainly just using the world map and city/ town names and removing everything else to fill in as they go.

my questions are 

1) Has anyone ever tried this?

2)  What to avoid to not let this get out of hand

and 3 ) How to reel it back if it starts to get out of hand

Check out the Eberron stuff for the technology side of things, even the dragonmarks could be something along the lines of MAKO infusions ala SOLDIER.  I would say try and decide what the core concept of each place is, and look for dnd analogues that exemplify that.  Midgar is a high tech (magitech) society with ruthless overlords.  Depending on how you feel I could see a dwarven influence or human (with maybe gnomes as their scientists) where all the other races are stuck in the plates areas. Cosmo canyon could be either a very nature magic oriented area, perhaps a place of learning for wizards and druids with an Elven bent.  Wutai could be the land of the samurai Dragonborn, or just a variety of rare species, elementals and such, sea god worshippers or pirates.  Or heck all of them together with a multi cultural land.

I think you jumped in too deep to start with.  Final Fantasy 4 would be a better setting as it starts out in a traditional medieval/fantasy setting and gradually introducing sophisticated technology.  

The more I think about it, it may not be so bad.  Twist the Eberron campaign setting and a number of the locales can match up moderately well.  Still going to be tough but...  if you wish to preserve some flavor of materia, you could have the occasional "magic weapon" be a stone that is socketable into anything and makes it a +1 fire weapon.  With that approach I would say have some fluff options akin to the minor properties section (under chapter 7 treasures, special features DMG).  

Also I would suggest instead sticking too closely to the source material you expand on it.  Wutai is kinda a one dimensional area that could be fleshed out with all manner of samurai, ninja, pirate, thieves and more.  The northern continent could be like xendrik  with ruins and old war machines.

Yeah, The plot of 7 won't work at all and will have to be replaced with a homemade one. I might keep the idea of Midgar but merge it with Nibelheim and  Kalm as one massive city. Gold Saucer might stay the same. I found a race of elves called Aereni that will fit well for Cosmo Canyon, Bone Village or Ancient Forest. Wutai makes sense as a type of  Home base for mercenaries.  Chocobos I can keep and just use Horse stats,  What I might use for a base story are Garland and his friends ( arch devils )

I like the idea of taking the setting from one FF and the characters (enemy goals) of another FF.  Could also use something like the AxeBeaks or perhaps one of the bipedal dinosaurs as a template.  Maybe Nibelheim is a research station or something along those lines.  Some kind of offshoot of the main civilization in midgar.  Kalm could be a town where those that didn't want to live in the city (or may have been cast out) live?  A simple somewhat poor lifestyle, could be where all the food is produced that Midgar must consume.  I wonder what kind of terrible beast will take th place of the Midgarzolom, maybe a purple worm or something like that.

A DM I played with tried to do that with the Land of Xanth.  Wow that didn't work. Way to complicated of a world. 

Maybe try something a little lower key, like jumping into a world populated by Amazons where the men are servants. 

Quote from bobberuchi >>

A DM I played with tried to do that with the Land of Xanth.  Wow that didn't work. Way to complicated of a world. 

Maybe try something a little lower key, like jumping into a world populated by Amazons where the men are servants. 

That sounds even worse to work around.

Not worse, just hard to swallow for some.

If you want to include a kind of Materia system, I would suggest something like this:

There are no "magic weapons" in this world, instead all mundane weapons have materia slots. The quality of weapons would determine the number of slots they have (0-5, as an example) and the strength of the materia would fill x number of slots, but only give a +1 to something based on the level of the materia. +1 to hit, or +1 to damage takes up 1 slot, +2 takes up 2 slots, +3 takes up 3 slots, etc. Certain higher powered abilities take up 4 or 5 slots. You might even want to develop unique "equip-able magic material" that can be slotted at 4 or 5 slots, but can only be used a limited number of times.

General magic also comes in the form of Materia as well, but to maintain balance and class uniqueness, it functions differently than in FF7. Certain individuals have varying skills regarding its use (conveniently the magic using classes are more adept). Non-magic users can consume a materia to cast the spell one time, with a +0 to the ability modifier (attack roll or saving throw DC).

Magic users have gained a "mystical ability" to more successfully use materia without breaking it. They can choose a number of materia to cast in a day limited by their classes ability to prepare spells in a given day. These follow traditional D&D spell casting rules, with the materia "recharging" after a long rest. Materia cast outside of the prepared limit follow the "unskilled" casting rule above. Rituals function as normal.

So basically what I ended up doing was Using the Crystal from Final Fantasy 1 as a huge Meteor and the shards are Materia one of the main NPC's kinda like Cid is one of the few in the world who knows how to refine it into magic weapons. So if they want that kind of power they have to find some and materials for them to make it.   

This is a really good topic, I've been home brewing a Final Fantasy setting that takes things from a lot of the Final Fantasy Multiverse to make my own. So far mine is going to be using elements of Crystal Chronicles, IX, XII, XIV (for at least one race) and a players would be flavoring the Sould knife rogue from Tasha's to be a lot like Noctic from XV. So far what I know is that It'll be a mix of high fantasy like the Final Fantasy Series but will have a fair bit Dark Fantasy elements with Lovecraftian eldritch horrors to see the darker aspects when they will be nescessary. So far I've put in about 4 or 5 months worth of planning on and off to get a lot of researched information together.

Good luck friend, and happy gaming.

I am trying to make a more dark fantasy version with the creator and the warring triad as deities along with some memorable summoners as spirits that are worshiped. I am stuck with domains for clerics and equivalent cosmology. Also thinking about cloud of darkness as a source for warlocks 

Quote from Khiset >>

I am trying to make a more dark fantasy version with the creator and the warring triad as deities along with some memorable summoners as spirits that are worshiped. I am stuck with domains for clerics and equivalent cosmology. Also thinking about cloud of darkness as a source for warlocks 

 As  far as Summons I can see Clerics for Alexander (LIfe), Diablolos  / Hades ( Death) Odin ( War), Others could be Ramuh ,Shiva, Livathian ( Deep one pact) , Gilgamash, Yojimbo, and Ifrit ( currently I'm using him for Wildfire Druid)