[NES] Freedom Force (USA)

[Dteyn]

Cannot Die (health will still decrease)
AAVATLEA

No damage from machineguns and most grenades
AEXALAPA + SZNAZESU

No damage from rockets
AEXAYEAA + SZNAYESU

Take less damage in later levels
PEOEYAZA + SZVEIESU

No damage from missiles 1P
SZOLLKSE

No damage from missiles 2P
SZELYKSE

Levels complete after killing 1 enemy
ENXTAYAP

Levels complete instantly
AEXTPYLA

Skip bonus round (still get the bonus)
ESNIXLEY

Freeze timer in bonus round
SZOIULVG

No errors in bonus round
SXUSVLVT

Infinite ammo 1P (alternate to Galoob code)
SXKVANVK

Infinite ammo 2P (alternate to Galoob code)
SXSTLNVK

Infinite errors allowed (alternate to Galoob code)
NNOVAYTE

No errors allowed (increase difficulty)
PEOVAYTA

Items stay on screen longer
NNSLIEGK + SGOLGEOS

Picking up .38 cal gives you grenade launcher 1P
ZASZVYAA

Picking up .44 mag gives you grenade launcher 1P
ZAKZOYPA

Picking up .38 cal gives you grenade launcher 2P
ZESZUYAA

Picking up .44 mag gives you grenade launcher 2P
ZEUXVYPA


Well, I had a lot of fun making codes for this game! I made about half these codes before checking the DB (bad habit of mine), then checked the codes DB and saw some of these are already worked out in RAW format. However I always try to make assembly code hacks where possible to make GG codes, so they can be used on a real console with a Game Genie.

A couple notable codes that really improve gameplay in my eyes are the "Items stay on screen longer" and the lesser damage codes. I find the amount of damage inflicted to the player to be excessive, considering if you die once it's game over.


PS: I also took a crack at making a "No screen blanking" code for playing this on an emulator, to try to get rid of the annoying screen blanking required for the light gun. I had success getting rid of the blanking and keeping some sort of hit detection, unfortunately though one shot will hit everything on the screen.

My work on it is as the end of the notes below. If any devs want to have a look at it that would be great! A working "no screen blanking" code would be awesome!


Code Development Notes:


Spoiler Alert! Click to view...

Cannot Die (both players, health will still decrease)
AAVATLEA

Initially I tried making codes to prevent the player's health from decreasing,
however it would require a lot of GG codes because there are multiple routines
for reducing the player's health.

Instead I focused on what happens when the player runs out of health to prevent
the player from dying.

An idle loop constantly checks on 1P/2P health remaining. If it falls low enough, 
a value will be loaded into $C3 which indicates player death. Changing the value 
loaded at $8365 will prevent player death when health gets to zero.

 06:8357:AE 16 05  LDX $0516 = #$00
 06:835A:A5 C1     LDA $00C1 = #$00
 06:835C:10 03     BPL $8361
 06:835E:AE 26 05  LDX $0526 = #$18
 06:8361:CA        DEX
 06:8362:8A        TXA
 06:8363:10 04     BPL $8369
>06:8365:A9 80     LDA #$80
 06:8367:85 C3     STA $00C3 = #$00
 06:8369:20 56 AE  JSR $AE56


   8366:00:80 = AAVATLEA

No damage from machineguns and most grenades
AEXALAPA + SZNAZESU

No damage from rockets
AEXAYEAA + SZNAYESU

Take less damage in later levels
PEOEYAZA + SZVEIESU

Health points deducted are stored at $83-$85, initialized here:

 06:806D:BD 9F 80  LDA $809F,X @ $809F = #$02
>06:8070:85 83     STA $0083 = #$00
 06:8072:BD A3 80  LDA $80A3,X @ $80A3 = #$01
>06:8075:85 85     STA $0085 = #$00
 06:8077:BD A7 80  LDA $80A7,X @ $80A7 = #$08
>06:807A:85 84     STA $0084 = #$00

$83 is used for enemy pistols, $84 for rocket launchers, and $85 for
machineguns and grenades. An indexed table is used for later levels.

Setting $80A3 to 00 causes enemy machineguns/grenades to do no damage.

For the code to work on every level, the indexed LDA (BD) must be
changed to an absolute LDA (AD).

   80A3:00:01 = AEXALAPA
   8072:AD:BD = SZNAZESU

Changing $80A7 will change the amount of damage rocket launchers do. It
also needs an indexing fix for later levels.

   80A7:00:08 = AEXAYEAA
   8077:AD:BD = SZNAYESU


After more playtesting I realized $0083 is also adjusted to higher 
multiples in later levels, resulting in lots of damage quickly. 
Setting it to a value of 01 results in less damage in later levels.

   809F:01:02 = PEOEYAZA
   806D:AD:BD = SZVEIESU

These codes work for both 1P and 2P.

No damage from missiles 1P
SZOLLKSE

No damage from missiles 2P
SZELYKSE

Missiles (on the last level) have their own code to hurt the player.
Normally a missile will do 22 HP worth of damage, pretty brutal considering
each player has a maximum of 24 HP.

 06:B3FD:A5 C1     LDA $00C1 = #$80     # Check for 1P/2P
 06:B3FF:10 0C     BPL $B40D            # If 1P, go to $B40D
 06:B401:AD 26 05  LDA $0526 = #$0C
 06:B404:38        SEC
 06:B405:E9 16     SBC #$16             # Deduct 22 of the 24 possible HP (2P)
>06:B407:8D 26 05  STA $0526 = #$0C
 06:B40A:4C 3B A8  JMP $A83B
 06:B40D:AD 16 05  LDA $0516 = #$00
 06:B410:38        SEC
 06:B411:E9 16     SBC #$16             # Deduct 22 of the 24 possible HP (1P)
 06:B413:8D 16 05  STA $0516 = #$00
 06:B416:4C 3B A8  JMP $A83B

Changing $B407/$B413 to a LDA will prevent this from happening.

   B413:AD:8D = SZOLLKSE (1P)
   B407:AD:8D = SZELYKSE (2P)

Levels are completed after killing 1 enemy
ENXTAYAP

Levels are completed instantly
AEXTPYLA

The counter for enemies killed is stored at $C2, and incremented in several places.

>06:A235:E6 C2     INC $00C2 = #$03
 06:A237:20 A9 AD  JSR $ADA9

Initially I tried changing $A235 to DEC $00C2, it worked initially however in later 
levels other code is used to adjust $C2.

Instead, I checked the read of $C2 and there is an idle loop that checks the value
and once enough enemies are killed it will jump to $E7E9 to end the level:

 07:E79E:A5 C2     LDA $00C2 = #$0A
 07:E7A0:10 03     BPL $E7A5
 07:E7A2:4C E9 E7  JMP $E7E9

Changing $E7A0 to a BEQ will cause the level to end after killing one enemy.

   E7A0:F0:10 = ENXTAYAP

A variation is to always take the branch to $E7E9 by zeroing the branch value.
This will end the level immediately.

   E7A1:00:03 = AEXTPYLA

Skip bonus round (still get the bonus)
ESNIXLEY

Tinkering with RAM I found that $0700-$0707 hold the letters on the bonus screen.
I set a read breakpoint and found this loop:

>07:DBE4:BD 00 07  LDA $0700,X @ $0704 = #$1B
 07:DBE7:C9 1B     CMP #$1B
 07:DBE9:D0 02     BNE $DBED
 07:DBEB:E6 10     INC $0010 = #$00
 07:DBED:CA        DEX
 07:DBEE:10 F4     BPL $DBE4
 07:DBF0:A5 10     LDA $0010 = #$00
 07:DBF2:F0 03     BEQ $DBF7
 07:DBF4:4C F7 DA  JMP $DAF7

The value at $10 seems to be a "round completion" register of some kind. It
normally contains 01 when the bonus round is running.

Changing the BEQ instruction to BNE results in the bonus round automatically 
ending.  Player still gets the bonus. :)

   DBF2:D0:F0 = ESNIXLEY

Freeze timer in bonus round
SZOIULVG

The value for the bonus timer is stored at $88/89.  
The code here decrements the second digit:

>07:DB13:C6 89     DEC $0089 = #$04

Changing this to a LDA prevents the timer from decreasing.

   DB13:A5:C6 = SZOIULVG

No errors in bonus round
SXUSVLVT

The error counter for the bonus round is stored at $A5.  
The code here increments it:

>07:DBBE:E6 A5     INC $00A5 = #$02

Changing this to a LDA prevents the error counter from increasing.

   DBBE:A5:E6 = SXUSVLVT

(so awesome that the code val/cmp is an inversion of the instruction at $DBBE. hah)

Infinite ammo 1P (alternate)
SXKVANVK

Infinite ammp 2P (alternate)
SXSTLNVK

The counter for remaining ammo is at $0515 (1P) / $0525 (2P). 
Ammo value is decremented here:

1P:
>07:E7C8:CE 15 05  DEC $0515 = #$24

2P:
>07:E7D3:CE 25 05  DEC $0525 = #$23

Changing this to a LDA gives infinite ammo.

E7C8:AD:CE = SXKVANVK
E7D3:AD:CE = SXSTLNVK

PS: I noticed after I made this that Galoob also has a code for Infinite Ammo, 
but it targets a slightly different region so I decided to keep this code.

Infinite errors allowed (alternate)
NNOVAYTE

No errors allowed (increase difficulty)
PEOVAYTA

The number of hostages killed is stored at $0517 (1P) / $0527 (2P).  The value is 
checked in several places, but this is the one that matters. If too many hostages 
have been killed the jump to $E98D is taken and then it's all over.

This code works for both 1P and 2P, because the routine at $C391 loads the
appropriate player specific value from $0517 / $0527:

 07:C391:A4 C1     LDY $00C1 = #$80
 07:C393:30 04     BMI $C399
 07:C395:BD 10 05  LDA $0510,X @ $0517 = #$06
 07:C398:60        RTS -----------------------------------------
 07:C399:BD 20 05  LDA $0520,X @ $0527 = #$06
 07:C39C:60        RTS -----------------------------------------

>07:E797:C9 06     CMP #$06
 07:E799:90 03     BCC $E79E
 07:E79B:4C 8D E9  JMP $E98D
 07:E79E:A5 C2     LDA $00C2 = #$00

Changing the compare to #$FF will result in the jump to $E98D never
being taken, so killing hostages won't end the level.

   E798:FF:06 = NNOVAYTE

A difficulty variation on this code is easy, simply making it so
that only one civilian killed will end the level.

   E798:01:06 = PEOVAYTA

PS: I noticed after I made this code that Galoob made one as well,
but it's slighty different (uses LDA instead of changing the CMP 
value) so I decided to keep this code.

Items stay on screen longer
NNSLIEGK + SGOLGEOS

The default item timeout seems to be random, sometimes items are on screen
for a couple seconds, most times they just flash and then disappear as soon
as you notice them. This sucks! I made a code to deal with this.

The value at $A1 indicates whether bonus item is available on screen.

 06:AEF6:A9 01     LDA #$01
 06:AEF8:85 A1     STA $00A1 = #$01
 06:AEFA:20 1F A8  JSR $A81F
   06:A81F:A5 87     LDA $0087 = #$00
   06:A821:0A        ASL
   06:A822:0A        ASL
   06:A823:0A        ASL
   06:A824:0A        ASL
  >06:A825:AA        TAX
   06:A826:60        RTS -----------------------------------------
 06:AEFD:BD 0F 04  LDA $040F,X @ $040F = #$00
 06:AF00:30 03     BMI $AF05
>06:AF02:4C 0A B0  JMP $B00A
 06:AF05:20 A9 AD  JSR $ADA9


A loop determines how long the item stays on the screen for by comparing
against the table starting at $B0D5:

 06:B011:BD 00 04  LDA $0400,X @ $0400 = #$12
>06:B014:D9 D5 B0  CMP $B0D5,Y @ $B0D7 = #$30
 06:B017:D0 07     BNE $B020
 06:B019:A9 00     LDA #$00
 06:B01B:85 A1     STA $00A1 = #$01
 06:B01D:4C 3B A8  JMP $A83B

Changing $B0D5 to $FF results in a longer screen time for the first item slot.

   B0D5:FF:4C = NNSLIEGK

The indexed compare (D9) also needs to be changed to an absolute compare (CD)
so that the long timeout value is used for all items.

   B014:CD:D9 = SGOLGEOS

This code works for both 1P and 2P.

Picking up .38 cal gives you grenade launcher 1P
ZASZVYAA

Picking up .38 cal gives you grenade launcher 2P
ZESZUYAA

Picking up .44 mag gives you grenade launcher 1P
ZAKZOYPA

Picking up .44 mag gives you grenade launcher 2P
ZEUXVYPA

I like using the grenade launcher, who doesn't? But when a .38 or .44 pops up
and you are firing the grenade launcher, you may lose it because you pick up 
the new weapon.  I made codes so that you always get the grenade launcher. :)

The weapon status indicator is at $C7. It's valid for both players.
   00 = .38 calibre
   01 = .44 magnum  
   02 = Grenade Launcher!

Picking up G.L:

1P:
 06:AF2B:A9 02     LDA #$02
>06:AF2D:85 C7     STA $00C7 = #$00

2P:
 06:AFA8:A9 02     LDA #$02
>06:AFAA:85 C7     STA $00C7 = #$00

========================

Picking up .38 cal:

1P:
 06:AF55:A9 00     LDA #$00
>06:AF57:85 C7     STA $00C7 = #$02

2P:
 06:AFD2:A9 00     LDA #$00
>06:AFD4:85 C7     STA $00C7 = #$02

Actually let's make that .38 cal a grenade launcher!

   AF56:02:00 = ZASZVYAA
   AFD3:02:00 = ZESZUYAA

========================

Picking up .44 mag:
1P:
 06:AF40:A9 01     LDA #$01
>06:AF42:85 C7     STA $00C7 = #$02

2P:
 06:AFBD:A9 01     LDA #$01
>06:AFBF:85 C7     STA $00C7 = #$02

Actually let's make that .44 mag a grenade launcher!

   AF41:02:01 = ZAKZOYPA
   AFBE:02:01 = ZEUXVYPA

INCOMPLETE/BETA CODE:
No screen blanking (for using emulators w/mouse click)
UINVOYOS + ENVGPLAZ + ZEVGZLZU

Major bug: screen blanking is gone but every enemy/hostage gets hit now.

I have an LCD TV and in order to play this game I use an emulator with a modded light 
zapper (wireless gyroscope bluetooth mouse, feels much like using a Wiimote).

As such I was looking for a way to remove the screen blanking that the game normally 
uses for the light zapper to operate.


The routine at $C3D1 is what handles the hit detection and blanking of the screen.

>07:EF78:20 D1 C3  JSR $C3D1

>07:C3D1:A9 AA     LDA #$AA
 07:C3D3:85 F0     STA $00F0 = #$FF
 07:C3D5:A5 FE     LDA $00FE = #$1E
 07:C3D7:29 E1     AND #$E1
 07:C3D9:85 FE     STA $00FE = #$1E
 07:C3DB:A9 00     LDA #$00
 07:C3DD:85 DE     STA $00DE = #$20
 07:C3DF:85 DD     STA $00DD = #$80
 07:C3E1:20 32 B5  JSR $B532
 07:C3E4:20 5D B5  JSR $B55D
 07:C3E7:20 00 C0  JSR $C000
 07:C3EA:20 00 C0  JSR $C000
 07:C3ED:A5 C7     LDA $00C7 = #$02
 07:C3EF:29 03     AND #$03
 07:C3F1:C9 02     CMP #$02
 07:C3F3:F0 09     BEQ $C3FE
 07:C3F5:A5 FE     LDA $00FE = #$1E
 07:C3F7:09 14     ORA #$14
 07:C3F9:85 FE     STA $00FE = #$1E
 07:C3FB:4C 19 C4  JMP $C419

It seems that $FE has to do with the blanking, also $DE/DD have to do with
palettes I believe.  The routine at $C000 seems to be a delay routine.

The first thing I tried is a simple hack, C3D1:60:A9 (RTS) but then no hits 
are registered at all on the screen. Go figure.

I was able to bypass most of this and keep the hit detection working by making
two patches.  First, I made the jump at $EF78 go to $C3DB, to skip over the
setting of $F0 and $FE to prevent the screen blanking.

   EF79:DB:D1 = UINVOYOS

Just doing that by itself however seems to break the hit detection.

Doing some playing around, I tried inserting a branch at $C3E1 to skip past
the four JSR's and end up at $C3ED.  This by itself makes the flashes much
quicker but the screen still turns black for a brief second.

   C3E1:F0:20 = ENVGPLAZ 
   C3E2:0A:32 = ZEVGZLZU

However combining these two patches seems to make the black flashes go away
and keeps the hit detection intact.  There is still a quick flash of garbled 
graphics that I believe are normally covered by the blanked screen, but it's 
less distracting than the complete blackout.

The new code flow looks like this:

>07:EF78:20 DB C3  JSR $C3DB

>07:C3DB:A9 00     LDA #$00
 07:C3DD:85 DE     STA $00DE = #$50
 07:C3DF:85 DD     STA $00DD = #$80
 07:C3E1:F0 0A     BEQ $C3ED

 07:C3E3:B5 20 5D B5 20 00 C0 20 00 C0 

 07:C3ED:A5 C7     LDA $00C7 = #$00
 07:C3EF:29 03     AND #$03
 07:C3F1:C9 02     CMP #$02
 07:C3F3:F0 09     BEQ $C3FE
 07:C3F5:A5 FE     LDA $00FE = #$1E
 07:C3F7:09 14     ORA #$14
 07:C3F9:85 FE     STA $00FE = #$1E
 07:C3FB:4C 19 C4  JMP $C419


After playtesting, I realized that this does actually completely break the 
hit detection.  Now every enemy/hostage is hit automatically no matter where you
aim.  Ahh crap.  Maybe I will revisit this code at some point. Would be awesome!