NES - Jackal (USA).NES hack
Jackal 2
author: RayofJay
date: 16Dec2019

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READ ME
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CHANGE LOG
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Version 2.1:  Original hack as described below

Version 2.15: Broke the hack up into several patches.  Also included a bullet direction hack

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Synopsis: This is a complete overhaul/hack of the game Jacakl for the NES.  The game is MUCH more difficult now, but life count is increased to offset this a little. 
Changes include:
enemy AI, logic, timers, spawn location, spawn location randomization (only a few of the enemies get this property - see the level editor and readme file for details), 
bullet speed, enemy health, palette changes, point values

level palettes, level layout, helipad light flashing speed, helipad palette update function has changed, screen repeat function (makes level longer), double digit life count

object function (level 3 lasers, level 6 escalators, etc.), 






SPOILER!!
be aware the below may spoil the fun of playing through game normally







Details:
NOTE: i recorded most of the changes made to the ROM, code-wise, in the accompanying excel file

Screen duplication (lengthening the game would be very difficult, as-in increasing memory size and adding more level data
	, so, instead, I added data for each level that dictates how many times each screen will be repeated (there is a small palette issue with this, but it doesn't detract from
	the game play so I did not resolve the issue).  most stages have this screen repeat function somewhere.)
I found then infantry to be almost useless and so most enemies are the more difficult tanks, but there're still a few infantry scattered about.
The death process is much faster with a lot fewer I-Frames (invulnerability on respawn), adding to the difficulty
main weapon explosion time is cut in half allowing for faster firing (you cannot fire again until the sprite completes the explosion)
Main wepaon damage now increments as you gain power ups
Max main weapon upgrade increased from 3 to 5
Previously, grenades and all bazook upgrades caused 5 HP damage.  Now, grenade does=5, B1=6, B2=7, B3=8, B4=9, B5=10.
The speed of each main weapon phase now increases with each successive increase from grenade to B1, B2...etc.
Death does not reset your main weapon power back to grenade.  Instead, it decrements (5 to 4, 2 to 1, etc.).  This is another offset for the difficulty as death is expected (a lot).
NOTE: Along with most enemy health increases, most enemies are now immune to destruction from the bazooka horizontal and vertical splash damage
Many more secret power ups have been scattered throughout the world.
Most enemies now give you more points to offset the difficulty
All bosses have been modded to increase difficulty
	Level 1: harder tanks plus 32 of them instead of only 4!!
	Level 2: faster status heads plus some turrets
	Level 3: faster turret bullets plus the terrain makes attacking difficult
	Level 4: swamp everywhere!  increase boss health.  sunken missile launchers (tile set change makes these look funny so i left it in)
	Level 5: increased tank health and 6 tank spawn shutters instead of 4.  increased tank shutter health (a lot)
	Level 6: increased first phase bldg and laser turret health.  
many more overhead helicopters fly by.  feels more like an assault now!  NOTE: the landed helicopter and the one that flies by halfway through the stage are independent of each other
some stages have more than one POW drop off heli
POW point values are massively increased, making this a great idea for staying alive (points give 1UPs faster), but keeping the POWs without dying trying to get to the helipad is hard.
You now gain 1UPs from getting points much faster to offset the difficulty
life count was previously capped at 9 and displayed as P#.  the life count now has no cap and double digit life count is displayed.
Power up star for 1UP now gives you 3 lives
	NOTE: these can all be seen by opening up the ROM in my level editor, but i highly recommend finding them the fun way.
enemy and object horizontal positions are (possibly!) randomized.  There are 3 sections where an object may appear when randomized 
	(somewhere on the left half, right half, or middle half of the screen).  This is discussed in the level editor.
You may find your path seemingly blocked, but the game is fully completable.  Please report glitches if you find them!
Level 1 has a wonderful nighttime palette and when your main weapon explodes, the palette changes to simulate the night being lit up!
Level 3 infantry truck now spawns a different enemy :)
Level 3 lasers are now moving death traps :) (my favorite object hack!)
hidden mines (level 4/5) now have a much smaller detection radius
	NOTE: while playing two player, it seems there are two different radius checks, one for each player.  Player 2 has a large radius of detection (original).
	I left this in place to add to the co-op experience!
Bomber planes now have framentation bombs (enemy jeeps throw the same bomb too)
Most enemies are much faster in terms of response and less waiting (red tanks, level 1 boss tank, silver tanks, flame tank, etc. are much more difficult due to this along with more health)
Bomber planes can have randomized flight paths (still linear)
Level 6 escalators no push up upward instead of backward
Final boss flashes!  it's actually part of the helipad flash logic.  Final boss already had max health.  i remains unchanged from the original.


I probably missed a few things, but that's the majority of it
The hack isn't perfect, but i think it turned out really well.  For instance, there's some strang graphical glitches when there's a LOT of bomber planes and fragmentation bombs.
This was a great lesson in level and game development and layout.  I appreciate what the original game developers went through creating this fantastic games!


most of the above are spoilers, but the following are things that you may want to find on your own

(SPOILER?) level 6 has a gate that does not explode.  instead you use an invisible escalator object to move through it.
(SPOILER?) i have placed the gate opening (after gate is destroyed) over some conrete walls for added gameplay.  some are randomized :).
(SPOILER?) a lot of gate opening objects are placed around the world in unusual places!  level 6 parked planes (some) are now destroyable, some level 3 crates, and other objects


Reference the accompanying Jackal Memory Usage.xlsx file for Jackal information regarding
	The layout of RAM
	The dissection of the ROM (data tables, logic, intent, modifications, etc.)
	Level Data
	Sprite Data

You may contact me at:
jpetheman@hotmail.com