Introduction:
I'm assuming that you're reading this because you have an interest in one of two things. You either want to write your own "FanDex" or you want to know why GW books are so 'hit and miss' with their balance (both among other armies and internally). Hopefully, I'll be able to answer those questions over the next few posts (that's right: this one's gonna be extra long. Borak - put the kettle on). We need to get some stuff out of the way though first, before we do:
1) This guide focuses mostly on Warhammer Fantasy
There's a few reasons for this. Firstly, Fantasy is the game that I play most often, and the only game that I've written a decent fanbook for. Secondly, Fantasy is actually the easier system to write and test for. 40k has become a very confusing landscape thanks to Allies, the additional slots on the Force Org charts, and the general sense of lunacy that comes along with that game. This is probably most of the reason that 40k is so unstable, and is definitely why I no longer play it. To write for 40k, I would first have to write an even longer thread about how to develop an entire ".5 system" from houserules. Not the subject here.
Therefore, whenever I can, I'll make a point/comment about 40k, but I'm aiming this guide at you Fantasy men (and women). Sorry 40k kids.
2) I'm no expert (or game designer), but I've done this before
Nothing that I say here is sacred. Just because I did things one way, doesn't mean that there aren't different (and possibly even better) ways out there. Obviously, you may not agree with my methods.
I have done this before however - I spent 2 years of my time producing and playtesting a Nippon armybook for Fantasy. This isn't a shameless plug, but the links to view this book are all in my sig. I'll probably reference it a few times over the course of the thread, just to provide examples of how my methods are divergent from the GW method. I've also helped a handful of other players develop regiments/characters and even a full armylist, as well as writing alternate lists for the High Elves between their editions (and wasn't terribly far off from the current edition, if I recall). Also, years of owning and playing several (about half) of the WHFB armies over multiple editions has helped me get a feel for how things work mechanically. My group collects the other half, with most of the collection focused on the efforts of my best friend. We... know some things. I'm also currently working on an Albion project.
3) My methods yield a different kind of army from both "Official" books, and most Fan Books
Most players who write a fan book go into the task with a goal: to write an army that others can put on the table against their friends. If you're only writing an army to use for yourself among your local group, this guide isn't really that useful for you. If your group is okay with playing against a "Movie Marines" or "Power of Wrathful Gods" type list, that's cool. But other players likely won't be able to convince their group to play against such an obviously overpowered book.
A lot of fan developers will preach caution and dial back the competitive side of their own lists, to make the book more friendly and give opponents an easier pill to swallow. I disagree with this practice. If you write a "soft" army, it's going to lose. Losing is no fun. I would rather write an army that can go toe-to-toe with a competitive list from any official book in the game, and still provide a challenging game for both players, and give you a chance to win. Losing isn't nearly as fun for me - I would get pretty tired of seeing my Samurai get their butts handed to them game after game with no hope of success.
However, I also don't want to have the same internal balance issues that the official books have. I don't want obviously worthless choices - I want to fix what GW has done wrong. I want to give players the opportunity to write a competitive list with as many different units as possible, rather than just spamming one in particular (White Lion spam with HElves, for instance). The result is that my books often look very powerful. There are no objectively bad choices - just good ones, and that can scare people. The actual result however, is that you have a book more akin to the current Chaos Warriors army: lots of choices for your lists, rather than "one list to rule them all". This take a lot of effort however. You're going to need to playtest every inch of this army, and that's a lot of time invested into games and development.
4) This is not a "reskinning" of another book
When I wrote Nippon I didn't make "Empire with Samurai Swords". A lot of suggestions were made that I should just use High Elves, or just use Dark Elves, or Empire, even Brettonia to create my Nippon book. The whole reason that I was creating the book however, was that while any of these books were good, none of them would create a perfect fit. My methods started with the basis that I wanted something unique. I wanted an army that had a different playstyle, different strengths and weaknesses, and different units than any other army in the game. Something that GW might have churned out if this were an "official" army.
If you can get by with a simple reskinning, then by all means: go that route. Empire->Cathay, Beastmen->Celts, Wood Elves -> Amazon, or High Elves -> Macedonian all work incredibly well. Since most armies go by a historical background, you can draw the parallels and usually go right there. It's easier, it's faster, and most importantly: it's still an "official" armybook.
Even if you don't reskin, it's still practical to have an idea of what a reskin might have been. I play my Nippon army as Empire if I don't have my opponent's permission to use house rules. Therefore, you'll see a lot of units which parallel the Empire (Handgunners = Handgunners, Samurai = Swordsmen, Ashigaru = Spears/Halberds/Archers, Kensai = Greatswordsmen, etc). However that doesn't mean that my Handgunners are anything like Empire handgunners, and I also have several units with no obvious Empire analog (Onii, Tengu, Dragons, Ninja, etc).
Well, that's just about everything. The obvious stuff that I could think of. If this is still something you're intersted in: the opportunity to create your very own army for Warhammer Fantasy, then by all means keep on reading!
I'm assuming that you're reading this because you have an interest in one of two things. You either want to write your own "FanDex" or you want to know why GW books are so 'hit and miss' with their balance (both among other armies and internally). Hopefully, I'll be able to answer those questions over the next few posts (that's right: this one's gonna be extra long. Borak - put the kettle on). We need to get some stuff out of the way though first, before we do:
1) This guide focuses mostly on Warhammer Fantasy
There's a few reasons for this. Firstly, Fantasy is the game that I play most often, and the only game that I've written a decent fanbook for. Secondly, Fantasy is actually the easier system to write and test for. 40k has become a very confusing landscape thanks to Allies, the additional slots on the Force Org charts, and the general sense of lunacy that comes along with that game. This is probably most of the reason that 40k is so unstable, and is definitely why I no longer play it. To write for 40k, I would first have to write an even longer thread about how to develop an entire ".5 system" from houserules. Not the subject here.
Therefore, whenever I can, I'll make a point/comment about 40k, but I'm aiming this guide at you Fantasy men (and women). Sorry 40k kids.
2) I'm no expert (or game designer), but I've done this before
Nothing that I say here is sacred. Just because I did things one way, doesn't mean that there aren't different (and possibly even better) ways out there. Obviously, you may not agree with my methods.
I have done this before however - I spent 2 years of my time producing and playtesting a Nippon armybook for Fantasy. This isn't a shameless plug, but the links to view this book are all in my sig. I'll probably reference it a few times over the course of the thread, just to provide examples of how my methods are divergent from the GW method. I've also helped a handful of other players develop regiments/characters and even a full armylist, as well as writing alternate lists for the High Elves between their editions (and wasn't terribly far off from the current edition, if I recall). Also, years of owning and playing several (about half) of the WHFB armies over multiple editions has helped me get a feel for how things work mechanically. My group collects the other half, with most of the collection focused on the efforts of my best friend. We... know some things. I'm also currently working on an Albion project.
3) My methods yield a different kind of army from both "Official" books, and most Fan Books
Most players who write a fan book go into the task with a goal: to write an army that others can put on the table against their friends. If you're only writing an army to use for yourself among your local group, this guide isn't really that useful for you. If your group is okay with playing against a "Movie Marines" or "Power of Wrathful Gods" type list, that's cool. But other players likely won't be able to convince their group to play against such an obviously overpowered book.
A lot of fan developers will preach caution and dial back the competitive side of their own lists, to make the book more friendly and give opponents an easier pill to swallow. I disagree with this practice. If you write a "soft" army, it's going to lose. Losing is no fun. I would rather write an army that can go toe-to-toe with a competitive list from any official book in the game, and still provide a challenging game for both players, and give you a chance to win. Losing isn't nearly as fun for me - I would get pretty tired of seeing my Samurai get their butts handed to them game after game with no hope of success.
However, I also don't want to have the same internal balance issues that the official books have. I don't want obviously worthless choices - I want to fix what GW has done wrong. I want to give players the opportunity to write a competitive list with as many different units as possible, rather than just spamming one in particular (White Lion spam with HElves, for instance). The result is that my books often look very powerful. There are no objectively bad choices - just good ones, and that can scare people. The actual result however, is that you have a book more akin to the current Chaos Warriors army: lots of choices for your lists, rather than "one list to rule them all". This take a lot of effort however. You're going to need to playtest every inch of this army, and that's a lot of time invested into games and development.
4) This is not a "reskinning" of another book
When I wrote Nippon I didn't make "Empire with Samurai Swords". A lot of suggestions were made that I should just use High Elves, or just use Dark Elves, or Empire, even Brettonia to create my Nippon book. The whole reason that I was creating the book however, was that while any of these books were good, none of them would create a perfect fit. My methods started with the basis that I wanted something unique. I wanted an army that had a different playstyle, different strengths and weaknesses, and different units than any other army in the game. Something that GW might have churned out if this were an "official" army.
If you can get by with a simple reskinning, then by all means: go that route. Empire->Cathay, Beastmen->Celts, Wood Elves -> Amazon, or High Elves -> Macedonian all work incredibly well. Since most armies go by a historical background, you can draw the parallels and usually go right there. It's easier, it's faster, and most importantly: it's still an "official" armybook.
Even if you don't reskin, it's still practical to have an idea of what a reskin might have been. I play my Nippon army as Empire if I don't have my opponent's permission to use house rules. Therefore, you'll see a lot of units which parallel the Empire (Handgunners = Handgunners, Samurai = Swordsmen, Ashigaru = Spears/Halberds/Archers, Kensai = Greatswordsmen, etc). However that doesn't mean that my Handgunners are anything like Empire handgunners, and I also have several units with no obvious Empire analog (Onii, Tengu, Dragons, Ninja, etc).
Well, that's just about everything. The obvious stuff that I could think of. If this is still something you're intersted in: the opportunity to create your very own army for Warhammer Fantasy, then by all means keep on reading!