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Jackal - NES super hack

Started by RayofJay, August 25, 2021, 07:32:34 PM

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hello, I have been on this journey since early 2019 and still going strong.  full level editor with BG and sprite graphics editing capability has been created, the ROM has been expanded - doubled in size, I have reverse engineered the entire source code, decompressed the majority of the graphics, expanded the levels from 12 screens in length to 45, and increased the game from 6 to 10 levels.  I have changed the points system to an XP system where players can purchase upgrades at the end of each level.


Looking forward to trying out the editor, I love playing with level editors.  :laugh:

Jackal was a game I always got into back in the day, so making/or playing a Jackal hack'll be a real treat. :D


If you have the inclination and the chops, I'd suggest coming up with a randomized level generator. You would have to figure out the heuristics for the level geography, progression toward a goal, placement of enemies, progression of difficulty, etc... Not trivial, but it sounds like you have come far already.

Then the game would have "infinite" replay. And you could explore modes like time trial, basic weapons only, pacifist mode(?!). Since you've got the XP system, maybe expand the abilities so you can buy a single-use nitro boost to go fast for half a second, but you can't shoot during that time. Or build a temporary dirtbag bunker you can attack from but not get hit. Or for every guy you rescue, you can fly the chopper for 3 seconds and rain death from above. I should stop there.

Just a thought. This is a clever game that I only discovered long after it came out, so I'm glad to see it get some love.


Very cool project. This is a nice game, and very "hackable". I started an editor of my own quite some time ago, but it was shelved because I had too many projects at the same time. Can you show some screenshots or is the project still in an early phase?


very interesting, have you thought about the title? would it be Jackal 2? or jackal trum


As I've told you before, this is incredible. But also, please fix the game's camera while you're at it! :laugh:


thanks for the replies!  i didn't expect as much interest in this older game :).
The newest level editor requires a patch  that i haven't really released yet.  If you're interested, DM me, or visit this discord:  or just DM me on discord.

here's the latest sample i uploaded to youtube.  doesn't include the XP menu though, but the menu works fine.

I feel like we talked before?  years ago?  i'm not sure.  The project already has a fully completed 1st hack.  here is my playthrough of it
It was extremely difficult for most, so i added patches for varying difficulties.
The latest hacking endeavor has seen me create the entire source code, and expand the levels, new enemeies etc, which is still fairly far from released.
Bogaabogaa has created a western themed level, and I have created an urban themed level with large city buildings, roads, etc.  And i'm working on level 1, but there's still 7 other levels to work on, new graphics and enemies.  It'll likely be a while before it's fully complete and ready to release.
I must admit, i'm not sure how to upload images or videos into this forum...this is my first time here.

A randomizer has certainly crossed my mind.  I think it's very doable - i already created an enemy horizontal position 'randomization' as part of my original hack.  It would certainly take some logic, but very doable.  i'm not if or when i'd get around to this, especially with the expanded hack taking so much time and effort.
I've already investigated changing the jeep speed.  it works form moving around on the screen, but when you scroll, it still scrolls one pixel at time due to how the game handle enemy spawning.  i haven't looked deep into what it would take to get that to work fully.  You'd have to make sure no enemy spawns or new level tile loads where missed..

I've thought about editing the title screen many times, and my original hack released (mentioned above) was called Jackal 2.  I think this new one needs a subtitle, like jackal, war march, or something. 

haha, the camera is certainly fixable.  i don't recall exactly what you were trying to fix though?  was it that the camera scrolled late when you were too close to the side of the screen?


Great Work!  :D


Quote from: RayofJay on August 26, 2021, 07:54:23 AM
I must admit, i'm not sure how to upload images or videos into this forum...this is my first time here.

I think you need to host your images somewhere else. I use imgur and copy the BBC code and paste it here.


In the background picture you see I struggle to display everything since my monitor does not have a high resolution. But high resolution should not be a problem to get in this time and age. Did not work with your editor in a while but I could do everything I need to get done.

Link to the editor I used here. OUTDATED EDITOR FOR EX ROM!

Source Assembly for the EX Source:
--deleted-- since it is a expanded full game. Use this patch instead ->

Editor Help:

Also worth noting. If you use Mesen the game will crash when loading stage 1. I think later stages work sometimes. The NES emulator FCEUX or loading the game on a flash card to play it on real hardware should work fine.

Here I showcase some of the western style level.
CV ROM DiscordServer


thanks for the links bogaa!

yes, Mesen crashes because of the mapper.  FCUEX handles it differently.  There is a mapper for Mesen that works, but that breaks FCUEX, but i don't recall the mapper number.  i only really use FCEUX.


My MMC5 conversion did work just fine till I updated to a newer Mesen version and the the bug did look like this. Sure it has to do that the CPU tries to play with the PPU while randering but did not dive into it for more then a day. I do not understand the mappers well enough to just spot when something behaves wrong and even after seening where it comes form I still need to find a solution to handle it different.
CV ROM DiscordServer


Quote from: RayofJay on August 26, 2021, 07:54:23 AMhaha, the camera is certainly fixable.  i don't recall exactly what you were trying to fix though?  was it that the camera scrolled late when you were too close to the side of the screen?
Exactly! A lot of Konami games have this problem. It shouldn't require the player to get so close to the edge of the screen to start scrolling.


Yes, the goddamn scroll thresholds that let you see no more than one third of the screen in front of you. This is a MAJOR flaw that makes the game a lot less enjoyable and needlessly difficult, mostly because you need cat reflexes to react to enemy presence. This is THE modification I would welcome with arms wide open.

Also, RayofJay, I do have a (probably old) version of your hack "Jackal 2" in my Jackal folder. I remember playing it, but I gave up after the first level because of the insane level of difficulty. But hats off to you for making the game a lot longer and with new tile sets. If I recall correctly, the game has a similar structure to Contra in many regards, like level tiles data and enemy placement and behavior code.


I found some code that changed how the side scrolled responded, so i was close to the solution.  i'll spend some time today on it

TRAX: Yes, i received quite a lot of negative feedback regarding the difficulty.  But, honestly, it's no different than SMW masters making Kaizo hacks.  I've played jackal most of my life and wanting something challenging.  Even with the insane difficulty, the fact that i made the levels makes it even a little less challenging to me personally.  However, i did re-release Jackal 2 with 3 separate difficulty patches on RHDN.  i do believe i including a doc detailing the differences in each difficulty level too.

August 27, 2021, 07:49:45 AM - (Auto Merged - Double Posts are not allowed before 7 days.)

the horizontal scrolling now begins 2 tiles earlier :).  The vertical scrolling already seems good to me?  thoughts?


Whoa, that's fast. What part of the code did you change?


Label1096: LDX #$00
LDA JeepHorizPosition,X
SBC #JeepMinimumHorizontalPositionForScrolling
SBC #(JeepMaximumHorizontalPositionForScrolling - JeepMinimumHorizontalPositionForScrolling + 1)
BCS ++
-: LDA JeepVertPosition,X
SBC #$60
BCC Label1134
SBC #$60
BCS Label1135
--: RTS
+: LDA $40
BNE Label1136
CPY #JeepMinimumHorizontalPosition
LDA #JeepMinimumHorizontalPosition
STA JeepHorizPosition,X
Label1136: DEC $40
LDA #JeepMinimumHorizontalPositionForScrolling
++: LDA $40
BNE ++
CPY #(JeepMaximumHorizontalPosition + 1)
LDA #JeepMaximumHorizontalPosition
---: STA JeepHorizPosition,X
++: INC $40
LDA #JeepMaximumHorizontalPositionForScrolling

Same location i sent you before, i just only edited one value before.  There's a check and then a set.  originally i just changed the check, but then the set made everything act weird (forced the jeep to jump around when the screen scrolled).  I replaced the values with global variables for ease of editing

August 27, 2021, 04:13:00 PM - (Auto Merged - Double Posts are not allowed before 7 days.)

video is short - 3-4 seconds.  be ready to click replay.  the static image of the jeep is approximately where it would scroll previously to give you an idea of the change.  The scroll point was moved 16 pixels.

Xander max

Very nice! Can the form you decompress u the game be used in other titles? Another thing, does your tool allow you to edit the vehicle?


the compression is konami RLE  this was removed from the majority of graphics and they are now uncompressed so they are all viewable in tools like yychr

yes, my level editor includes most BG and sprite graphics for editing, including the jeep.  the jeep is generated from mirrored tiles though so things like an isometric view arent possible.  at least not without sacrificing precious pattern table space and modding the sprite rendering routines


Nice, this is something I was thinking about a few weeks ago.

Will you change/update graphics or try something wilder after?


bogaa was already created a wild west theme stage.  level 7 is all urban.  level 1 is now more of a beach and river level.  and yes, all the other levels will likely get at least a retouch on the graphics.  the brand new levels will likely have brand new graphics.  new sprites are a little trickier be ause the sprite render table is already about full.  it shouldnt be too hard to expand it though

August 29, 2021, 10:45:53 AM - (Auto Merged - Double Posts are not allowed before 7 days.)

i have now incorporated a patching function directly into the editor - if the original Jackal USA.nes ROM is loaded (various bytes are checked), then an internal IPS file is applied.  The IPS format is extremely simple and I implemented the algorithm in the editor code

August 29, 2021, 02:17:50 PM - (Auto Merged - Double Posts are not allowed before 7 days.)

Level 7 sample: