What's the current state of tools used in story or progression modpack creation for 1.12.2? I want to try my luck at creating one, but I don't know enough about this.
OK, so I can only offer suggestions based on what I've seen done in existing modpacks; I don't know how helpful that will be though. Modern Skyblock 3: Departed seems to hide or block recipes until a certain stage is unlocked in the quest book (in the latter case, offering a tooltip mentioning which stage needs unlocking first). I'm not sure how it does this, but I
think it uses the vanilla recipe system present in 1.12.
In SevTech Ages, a similar method is used, in that certain recipes are just plain hidden until you reach that stage; in the case of SevTech it uses the Advancements system (with the mod Better Advancements) to lay out the progression path, and stages progressively unlock as you achieve certain Advancements. Anything you have that's above your stage is listed as an "Unfamiliar Item", and while they can be picked up and go in your inventory, if you try to hold them in your hotbar the item immediately drops on the floor.
Forever Stranded: Lost Souls has quest book, with certain chapters required to unlock others, however it uses a different system in that it gates blocks and items behind a set of "skills" - you spend XP to level these up, and items cannot be used, blocks cannot be placed etc if you do not have the correct skills at the required levels.
As for story, I haven't seen much done with that; Modern Skyblock is very much all about teaching you to use different mods (mod recipes are almost entirely unaltered) and obtaining resources using the Sky Resources mod. I would say, that offers some really interesting alternative ways of crafting things. FS:LS only has story in start chapter of the book, there's not much else. Likewise, SevTech is a primal, slow learning and progressing experience that has minimal outside prompting beyond the advancements, to keep the "feel" of the pack I think.
I suspect that with a bit of imagination you could turn a number of these various facets that different packs use towards whatever progression feel you want. As for story, I'm not sure; I don't know whether you could have progression chapters hidden until you visit a location or not, but I'm sure there's something of an RPG feel you could give a pack if you wanted to. I don't know how Sprout went about things, but I heard that had more of a roleplaying feel to it.
EDIT: Hopefully a nice simple question:
Does anyone know what mod adds in the 3D rendered fish that swim about in the water in SevTech? They look amazing, and I'd basically want them in any custom pack I put together 
So;
Just A Few Fish is the mod I was interested in
