I love Roguelikes and random items given from chests (and preferably also from monsters, but that seems quite difficult to program) which is why I am a big fan of the FFV Ancient Cave Hack. I was thinking of making something similar to that for FFIV.
Preferably you would choose your starting party, then set off to random maps, collect random treasure, until you reached certain floor numbers where you would fight bosses. Now a clear and present problem would of course be "So I get the Crystal Sword at game start. Looks like I can just plow through the game." To limit this I plan on implementing a Saga-esque system of Item Durability. Every weapon you pick up will be a x10 Quantity. So yes, you may get that first chest Crystal Sword, but you'll have to use it sparingly. And as seen recently I managed to fix the Infinite Arrow Bug so that will no longer be a portion of concern. The durability system is A: to prevent people from using only the higher end equipment they may find. B: Prevent people from staying in one area forever to grind. C: Present a rationing system that was not present at all in the original.
Now this leaves Armor... If the RNG is set from 00-FF you may get Nothing (fine with that), Sort, TrashCans (not fine with those) and you may get Adamant Armor. Game Over. You win. So because great armor in the early game can really imbalance the game Armor of every sort will only be dropped by Monsters, which will ideally not have such a high randomness (as in you won't go from fighting Imps to Gargoyles). And every monster will have their Item Drop from 1 to 2 to increase the likelihood you'll have armor.
So far I have found the "Give Item" Routine and found a cursory 00-FF byte to use, but that's clearly not ideal. The x10 Quantity, the way to equip multiples of an item, the way to fix the Infinite Arrow Glitch. Setting up a room with all Party Members that deactivate when you take them with you (thereby preventing any duplicate party members) is an easy enough event sequence to build.
While Ancient Cave is a lot of fun there aren't that many dungeons and rooms represented. But I'm not even sure how I would go about making it so the maps chosen are valid or if the coordinates will be correct in FFIV. If I can't get that to work I might just have to go for a straight "Dungeon Adventure" (which was recently done for Zelda 64, that too is a very enjoyable hack.) Choose your party, all chests will be randomized. Monsters will drop Armors (possibly healing items as well if I can't get some CMP set up that checks between Items and Weapons). Dungeon Bosses will be at the end of their respective dungeons (Now I might be able to make events have random battles so when you reach the end of the Mist Cave you might not be fighting the Mist Dragon the only possibility). And clearly some classes will need rebalanced. Otherwise there are just some characters people will never use. Why use Dark Knight Cecil, Tellah, Porom, Cid, and Edward when you could use the normal Final Party (which is the best party it seems)?
These are my preliminary ideas, but they are far from perfect. Does anyone have any thoughts on how to proceed with anything I said above, or have any suggestions of their own?