Maybe I'll try it at some point since my idea basically involves stripping the game of most of the equipment and replacing it with scrolls (no view weapon) of martial arts. I'll probably have to rework every single monster, and make some new graphics, though.
Which brings me to my first question: Can you create a weapon that uses the unarmed skill? Alternatively, can you rename skills or create new ones?
Now for some random ideas I'll toss out.
Perhaps instead of having scrolls as weapons, you could learn them from a dojo master. Arts could be differentiated by the skill they use, grappling for Judo, knees/elbows for Muay Thai, legs for Taekwondo, Open palm for Karate, fists for Boxing, and other such things, credit to Chaostrom for parts of these ideas
Fist wraps (So you can theoretically punch harder)
Jeet Kune Do (high chance to block?)
Capoeira (high chance to dodge?)
Ippo's boxing gloves (randomly scream SENDOUUUUU, enemy has chance to fall unconscious)
Styles of Hokuto Shinken (Throw in random ATAH! after some attacks :>, enemy has chance to randomly explode)
Styles of Nanto Seiken (does cut damage)
Taizen Tenroken (Not sure yet)
Self-taught fist (From Juza, not sure yet)
Various martial arts outfits
Leather suits like those that the punks in Hokuto no Ken wear
Kenshiro's outfit (gets torn to shreds easily, is it possible to make something repair itself and do something special when it's torn?)
Zangief's thong (Comes with chest hair? Gives bonus against bears, random chance of FWAINAL AATOMIC BASTAAHHHH)
Blubber (From Mr. Heart, maybe needs to be overfed to wear, figure out how to do that?)
Head guard (Like for sparring)
Hair styles as helmets, like a mohawk
Jagi's helmet (Turns you chaotic, like neerc se-ulb)
Toki's headband (Turns your hair white, makes you cough up blood, also makes you a huge badass)
Shotgun (Wand of striking)
Bazooka (Wand of fireballs)
Judging by the way I'm starting to take this, I think the majority of enemies would be mohawks, fang clan, bandits, etc.
Possible named enemies:
Maybe change Ippo into the sumo, gives his gloves after winning the match
Any of the masters
This gets complicated, as some of those that I mentioned that could work for gods, say, Jagi, and Raoh, would be perfect as a named boss and possibly the final boss, but then how could you pray to someone that's still alive and be rewarded for it?
Masters (Gods) (Missing a few):
Instead of praying, you communicate with them via meditation, this way it can work if they're still alive or dead, kudos to Chaostrom for this idea
Hokuto users (and what they may give): (Ranked roughly on skill/knowledge)
Kenshiro (Hokuto Shinken IV/Kenshiro's getup)
Raoh (Hokuto Shinken III)
Toki (Hokuto Ujoken/Toki's headband)
Koryu (Hokuto Shinken II)
Jagi (Hokuto Shinken I/Jagi's Helmet)
Amiba (Amiba-style Hokuto Shinken)
Unique users (and what they may give): (Ordered on lawful/chaotic stance)
Juza (Self-taught Fist)
Ryuga (Taizan Tenroken)
Mr. Heart (Blubber, lots of AC, maybe needs to be overfed to utilize properly?)
Nanto users (and what they may give): (Ranked roughly on skill/knowledge)
Shin (Nanto Koshuken)
Juda (Nanto Kohakuken)
Rei (Nanto Suichoken)
Shew (Nanto Hakuroken)
Thouther (Nanto Hoohken)
Environment would ideally not be underground, but could work anyway, perhaps substitute rock for something like concrete to emulate buildings or simply have fewer walls and more rooms, dungeons are inside of buildings, some outdoor stages.
There would have to be a LOT of flavor text to make any semblance of difference in most of the weapons.
If someone decides to make this but wants to clean it up, the Hokuto no Ken stuff is obviously the main focus and the Hajime no Ippo stuff like the boxing gloves and head guard could go.
If there's a way to limit weapon usage based on SKILL instead of STATS, then there could be multiple pre-requisites for Jeet Kune Do, or some other martial art, and you would have to move up the tree of nanto and hokuto users, learning more and more from the various masters until you're able to appropriately apply the techniques taught to you by Kenshiro. Let's not think about Kenshiro not teaching you due to the rules for now.
The basic setting could be that the Nanto users have declared war upon any and all people that use Hokuto Shinken in any form at all, no matter what purpose they served, kind of like the Koei Original story from Fist of the North Star Ken's Rage.
Random ideas pasted from IRC/added on a whim
<Somagu> I'm not sure how I would handle materials, but besides that I'm sure I could find a way to set the various martial arts apart from others
<Somagu> With a little studying, at least.
<Somagu> If there's a way to make it not show the material name, then I could just make the scroll's appearance either somehow static or use the secondary material.
<Somagu> Actual scrolls would have to be replaced with something else
<Somagu> Perhaps enchantments could reflect how advanced your technique is
<Somagu> Ippo, Kenshiro, Rei, Jagi, Raoh, etc. can be gods
<Somagu> Which would work well for the artifacts
<Somagu> Fountains could be vending machines
<Somagu> A lot of the things I'm suggesting I'm pretty sure would require source modifications however, or are even impossible
These are just random ideas I'm tossing out, I'm 95% sure this will go nowhere.