[Dashman]

Originally, Julius Mode was meant to be based on Castlevania 3, as each character plays like they did in that one (Julius like Trevor, Yoko like Sypha, Alucard like... Alucard). The only one out is Hammer who would play like Grant. It's hinted that Hammer was scrapped as playable during development.

They probably got to the point in which somebody said "alright, now we need someone to take the role of the ceiling-crawling ninja-pirate", followed by nervous looks at the design of Hammer and finally a "nah, it's alright, nobody liked Grant anyway...".

@sjdswanlund
I feel like the whole thing you suggest falls more into the "game making" category rather than romhacking.

[ginja_ninja]

Yes, I assume most people already have an .iso patched with the translation so it would be smart to work from that. Wonder how the files are structured it being a non-localized Japanese game and how much that would complicate things for people who only speak English to understand.

[OneCrudeDude]

In Thunder & Lightning for the NES, they annoyingly swapped the sound channels around.  Most games use Square 1 for the main melody and Square 2 for the backing melody, but this does the opposite.  This wouldn't be a problem if it wasn't for the fact that the sound effects play using Square 2, making the music entirely lopsided and quiet because the backing channel is playing.  So you'd either need to swap the music channels around, or swap the sound effect channels.  If I knew how, I could probably do it myself.  But seeing as it's an NES game, something as simple like that might need work akin to reprogramming the entire sound system from scratch.  Why is doing anything for the NES almost prohibitively difficult?

[FAST6191]

As tempting as it is I will leave out the "bug or feature" discussion.

If there is one phrase anybody with a trade is attuned to then it is "while you are here...", however a close second is anything that can easily be, or indeed is, phrased with the word "just". For the record as well it is not going to get that much easier/less tedious, though possibly for slightly different reasons, if you move to newer consoles/devices and want to change whole tracks/songs, single instruments/samples sure in some cases but not whole songs.
On the NES being hard... well the NES was a kind of low powered embedded device in an era when everybody had/needed their own custom embedded devices to get stuff done. Being low powered but in an era when everybody was used to such things meant they tended to extend the power of the device, though Nintendo did allow for this, at the cost of being slightly harder to work with (not a particular issue if you were the one that made the change).
One reference to the NES audio setup
http://wiki.nesdev.com/w/index.php/NES_APU
A more visual one, though it technically leaves out of some of the oddities
http://www.youtube.com/watch?v=la3coK5pq5w

In the absence of something more high level (read at emulator level) your two approaches as the ones I would be using/contemplating. Now if you are sure square 1 is never used for anything else in the game, or at least nothing else where there might be SFX, then you can figure out where its sound setup is located easily enough.
square 2 might be harder but looking at some gameplay then if you can hold off releasing the ball then you do not appear to have any extra effects. If not then pause menus and sound tests (I did not see either for this game at this point) are often good things.

As a first pass I would probably try disabling square 1's normal inputs and then doing a high level redirect of square 2's non sfx stuff to square 1 (manually take 8 from the address to get it into square 1's register, if indeed the game does add 8 to get it in square 2).

Anyway yeah this is going to take assembly rather than learning a format and acting in accordance with it, however it should a simpler kind of assembly (you are watching and changing addresses).

Redirecting the sfx instead is a viable option, however I would probably only do it if each level/stage had its own audio tracks and this one did not appear to in the video (some half hour) I skipped though for this.

[Vanya]

Hyper Zone would make a good base for a Star Fox prequel hack starring James McCloud.

[OneCrudeDude]

@Fast:  Thunder & Lightning only has 6 songs, three of which are "proper" songs that loop.  The third song is the only one that can be interrupted by sound effects, and the only song that plays in-game.  That said, what I meant by the NES complicating things more than they have any right to be is akin to make something as simple as a sparkplug change require the user to disassemble the entire motor, and not just pull off the cap that covers said sparkplug.

[KingMike]

A short time ago Tomato finished playing/streaming this Japanese FF6 ROM hack, FF6 T-Edition. Very interesting as it added a ton of sidequests, different spells, enemies, etc.

... so I don't know why I had a dream of a Secret of the Stars mod.
(although it did have a couple interesting features, like two parties, combo magic, classes (though not really used except to enable characters to use combo magic), a town-building feature (though not as diverse as BoF2). Maybe those could've been interesting if more work had been done on them in the game's development.)

[CM30]

Personally, I want to see a Luigi's Mansion type game for SNES.  Heck, maybe even a 2D 'demake' of Luigi's Mansion Dark Moon, with similar locations, music, ghosts/bosses, etc.  Someone was making something like this as a Mario fan game a while back (under a name like 'Luigi's Mansion 2D'), but unfortunately, it was cancelled.  Heck, it'd even be good just to see some of these MIDIs make it into a SNES title:

https://www.youtube.com/watch?v=3nmi7Rak-Wo

https://www.youtube.com/watch?v=OyzS_S9Toog

https://www.youtube.com/watch?v=I_j4oJCKqek

I also kind of wish to see a Doctor Who style game for a retro console (ideally the SNES, Genesis, GBA, etc). We've never had a good game based on that series (ROM hack or otherwise), and to see an actual puzzle platformer/adventure game where the Doctor has to stop alien plans while avoiding foes like the Daleks, Cybermen and Weeping Angels would be awesome. You could even use this as the intro (although you might need to update it to the series 8 one, given Peter Capaldi's Doctor has a different intro sequence):

https://www.youtube.com/watch?v=ZDuORTbSRXM

Someone made this fan animation (based on Pokemon, Final Fantasy, etc), which makes almost depressed it doesn't actually exist:

https://www.youtube.com/watch?v=RvSk1rosmYY

Finally, while it's again not something I'd have interest in making, I think it'd be kind of neat to see an attempt at porting the Castle of Illusion series to the SNES. Their graphics are definitely possible on Nintendo's console, their music is definitely possible on the system and honestly, I don't see a whole lot in the level design that wouldn't be possible either. So I'd love to see someone go further than me (I've ported much of the Toyland stage into my last two ROM hacks) and try and take on the rest of the job.

Just some ideas I thought would be pretty cool.

[Tirlititi]

This one is hilarious (the DW fan animation) 

[DragonDePlatino]

A Yume Nikki fangame using the Earthbound Zero engine. 'Nuff said.

[DougRPG]

A short time ago Tomato finished playing/streaming this Japanese FF6 ROM hack, FF6 T-Edition. Very interesting as it added a ton of sidequests, different spells, enemies, etc.

Yes, but it's in japanese, so it's not a hack for most of us here. 

[Winged Cat]

Fighting Masters (Genesis) - it would be nice to unlock the last boss as playable character in versus mode and add the possibility of appearance of the Moon arena in versus mode.

Dolucky's a League Soccer (SNES) - it would be nice to unlock the 5th team of moles (it can be unlocked via cheat-code at the title screen: Up, Left, Down, Right, B, Right, Down, Left, Up, Y, Left, Right, Up, Down, X, L, R)
In versus mode there is only one arena. I think that it would be hard to add the appearance of other arenas in random order, especially because of settings that can change the size of arena, add mines, walls and race tracks.

[FAST6191]

Fighting Masters (Genesis) - it would be nice to unlock the last boss as playable character in versus mode and add the possibility of appearance of the Moon arena in versus mode.

Dolucky's a League Soccer (SNES) - it would be nice to unlock the 5th team of moles (it can be unlocked via cheat-code at the title screen: Up, Left, Down, Right, B, Right, Down, Left, Up, Y, Left, Right, Up, Down, X, L, R)
In versus mode there is only one arena. I think that it would be hard to add the appearance of other arenas in random order, especially because of settings that can change the size of arena, add mines, walls and race tracks.

Adding boss characters to vs modes can be troublesome, especially if said bosses are considerably different to normal player sizes (memory issues), movement (hitboxes) and movesets (fairly obvious). However it has been done on several occasions.

" it would be nice to unlock the 5th team of moles (it can be unlocked via cheat-code at the title screen: Up, Left, Down, Right, B, Right, Down, Left, Up, Y, Left, Right, Up, Down, X, L, R)"
In my experience one of two things happens when you enter a cheat like that
i) The game sets a flag somewhere in memory.
ii) The game branches to something else somewhere.

In this case I would bet on i) if the game does not do anything after entering the code (save perhaps an audio/visual cue, if it actually jumps to a game then my bet changes to ii). There may be several flags set in memory as it notes what keys were pressed in what order but you probably only want the end one.
Both make for pretty good introductions to assembly hacking. You can pull it off in all sorts of ways. The basic way would be to convert it into a more general cheat if it is a flag in memory, a step after that would be to force the game to change that flag regardless and a later one would be to have it always take the "check passed" route when it reads that part of memory. If it branches/jumps then you need to take the same branch/jump, you probably will not be able to make a conventional action replay/gameshark/codebreaker cheat to do it though.

[Vanya]

Yes, but it's in japanese, so it's not a hack for most of us here. 

Well that's what translations are for.
From what I understand the ROM was expanded so translating it shouldn't be too difficult, no?

[Jeville]

Implement the completely pointless points system from the first Megaman game to the sequels.

[M-Tee]

Haha, I would actually dig that, especially if the majority of health and weapon power-ups dropped by enemies were also replaced by the little red point balls as well.

[Clippit]

In the same fashion people swapped and ported pretty much any kind of character model in Super Smash Bros. Brawl, I would've loved to see this kind of thing on the PS2, like putting Slash or Steven Tyler from Guitar Hero into Tony Hawk Underground 2, or the other way around, Tony Hawk, Gene Simmons or... Ben Franklin into Guitar Hero, or... uh... how about Gitaroo Man into Guitar Hero? 

[OneCrudeDude]

I've been inspired by CyberFox's ideas, so let me ask someone to hack Wrath of the Black Manta to replicate the now infamous opening scene from The Dark Knight Rises.  The ninja would be turned into the CIA agent, while the first boss would be turned into a version of Bane who has a much bigger head than usual.  All the cutscenes from the game will be imitations of various shots from that plane scene.

[TheLuigiLightning]

I Really want someone to do a Battletoads NES ROM hack.
I've mastered the original game, and I want someone to make new levels so I can relive that awesome experience.
The thing that really pisses me off, though, is that there is no utility for hacking Battletoads.  Why is there one for Battletoads and Double Dragon, but not the original?!  That has to change!  Someone needs to make a utility for level hacking Battletoads, and a level hack must be made...!  ...Whether someone makes it, or I have to make it myself...

[Negative Hippie]

I'm not entirely sure the level of difficulty that this would require, but a hack of Final Fantasy Tactics Advance that had some or all of these ideas would be great.

1. Speed up text and character movement
2. Ability to disable attack animations (replaced w/ a general attack animation for a character when they do magic, phys, healing, etc.)
3. Skippable cutscenes

I saw that someone had some other small fixes, and it helped me realize that FFTA is actually a really solid game with simple problems that hold it back to an awful degree.