Hacking the SNES ROM

[David]

For me in the ROM I sent to you and the current one, it is still appearing even when the byte at 0xE9C2 is 0x0D; I even wrote 0C or 0B and it still appears on Levels 12 and 13; perhaps something in the hacks tab is wrong?

Ah, I guess you're using the level select menu.
I tried it using generated passwords.
It seems the two ways of starting a level work slightly differently.

At 0xF76D write 0x0D.

[David]

There's a new link with the latest ROM on the description of the same Level 8 bug video I sent to you on PM on Nov. 23rd

I played though the game to test it. I hope you don't mind!

Here are my observations:

* Level 1: In the room before the sword, next to the spikes, the wall corner is not visible.

spikes_no_corner.png (22.11 KiB) Viewed 35864 times

* Level 1: In the top-left room of level 1, the ceiling is not visible. The room-above link is 254, but it should be 255.

* Level 2: I see you added spikes in the last pit of level 2. That's to prevent getting stuck, right?

* Level 4: The button which opens the gate to the big potion should open another gate as well (see screenshot).
Without that, after I got the big potion, I have to go the bottom route, and the guard down there kills me unless I already killed him before I started my way to the big potion.

gate_not_open.png (12.94 KiB) Viewed 35864 times

* Level 4 and 10: Is there any reason some doortops were changed into walls?

* Level 5: In the shadow's room, if you press the opener button (which is actually in the other room), the closer button will also get pressed.

* Level 5: The yellow guard has the amazon's voice.
* Level 7: The first guard has deep voice.
* Level 8: The last guard has deep voice.
* Level 10: The yellow guard doesn't grunt.
At Hacks -> guards -> guard voices, you should disable everything except Fat, Jaffar, and Skel.

* Level 7: In the purple guard's room, I see you made the top floor shorter. Why?

* Level 12: I see you recreated the disappearing sword using broken room linking. Clever!

[Shauing]

For me in the ROM I sent to you and the current one, it is still appearing even when the byte at 0xE9C2 is 0x0D; I even wrote 0C or 0B and it still appears on Levels 12 and 13; perhaps something in the hacks tab is wrong?

Ah, I guess you're using the level select menu.
I tried it using generated passwords.
It seems the two ways of starting a level work slightly differently.

At 0xF76D write 0x0D.

Yup, that did it. Thanks.

There's a new link with the latest ROM on the description of the same Level 8 bug video I sent to you on PM on Nov. 23rd

I played though the game to test it. I hope you don't mind!

Fine with me, you pretty much deserve it with all the hacking work and effort, as well as being an indirect playtester (now an official one as you played through it), but I hope you play the finished version when the new graphics and music are implemented and the oversights corrected!

Here are my observations:

* Level 1: In the room before the sword, next to the spikes, the wall corner is not visible.
* Level 1: In the top-left room of level 1, the ceiling is not visible. The room-above link is 254, but it should be 255.

Good catches! I have now fixed them.

* Level 2: I see you added spikes in the last pit of level 2. That's to prevent getting stuck, right?

You got it, and the Level 9 one is also fixed by making the left switch also open the door next to it.

* Level 4: The button which opens the gate to the big potion should open another gate as well (see screenshot).
Without that, after I got the big potion, I have to go the bottom route, and the guard down there kills me unless I already killed him before I started my way to the big potion.

Whoops, I never caught this perhaps because I always skipped the close switch on my way to the big potion. Though I can also say the map I downloaded from popuw does not indicate that that button should open the previous gate. I played the DOS version again, and you're right, it should open that gate as well. I fixed it as well.

* Level 4 and 10: Is there any reason some doortops were changed into walls?

Another odd oversight...from the SNES developers. The top part of the door top graphic doesn't exist, thus this graphical issue exists:

SNES Graphical Oversight.png (16.93 KiB) Viewed 35855 times

Also, when climbing next to it this graphic anomaly also occurs:

Climbing Graphic Oversight.png (16.55 KiB) Viewed 35855 times

Thus, walls were added in order to not change puzzles/level design and that the graphics look correct. I cannot add this graphic myself as the still Work-in-progress tool only changes character sprites.

* Level 5: In the shadow's room, if you press the opener button (which is actually in the other room), the closer button will also get pressed.

Huh, thought this was a SNES bug, but I didn't know that it seems that if a trigger is shared, all the buttons with the same trigger will display the pressed graphic.

* Level 5: The yellow guard has the amazon's voice.
* Level 7: The first guard has deep voice.
* Level 8: The last guard has deep voice.
* Level 10: The yellow guard doesn't grunt.
At Hacks -> guards -> guard voices, you should disable everything except Fat, Jaffar, and Skel.

That was also one of the changes pending to do, at least the guards with the ''skel'' grunt; I was debating whether to keep the amazon's voice and add it to some of the guards just to have a few female guards, but perhaps this won't fit and I already did that on ''The Queen Of Light''. On DOS though, none of the guards have voices.

* Level 7: In the purple guard's room, I see you made the top floor shorter. Why?

Spoiler: show

To prevent this shortcut/skip; it is the only major DOS skip that it is still possible to do in this version.

* Level 12: I see you recreated the disappearing sword using broken room linking. Clever!

Ha ha, you discovered it! Back when I was doing this, I was going to ask for a hack, but I figured this idea, and worked well enough.
This reminded me that I still need to change the shadows colors; wasn't there a palette that displays similar colors to the DOS one when the Shadow's specific palette is not specified/loaded in certain rooms when crossing a mirror? That happened to me on ''The Queen Of Light'' when the shadow appeared after crossing through mirrors in rooms where his specific palette is not loaded.

I'm delighted you played through this and spotted a few oversights that needed to be fixed and changes that I had to do. If some of the graphical ones can be fixed differently somehow, tell me how.

I hope to have the mod ready before the year ends, or at least for January 3rd, 2020, though I will miss the actual ''30th'' anniversary. Then again, I don't want to rush things a la ''Sonic 2006'' and release an incomplete game/mod.

[Norbert]

Oe, interesting to see these screenshots.
Such a unique project.

[Shauing]

Oe, interesting to see these screenshots.
Such a unique project.

Hopefully a trailer will be released in these days when I finish implementing the prologue music and some graphics

[David]

You got it, and the Level 9 one is also fixed by making the left switch also open the door next to it.

I didn't notice that in my playthrough; but now I checked it and it's indeed so.

Huh, thought this was a SNES bug, but I didn't know that it seems that if a trigger is shared, all the buttons with the same trigger will display the pressed graphic.

The same happens in the second room of level 9.

Actually the DOS version has this bug as well, but the other buttons with the same trigger are usually not redrawn immediately, so it's less visible.
It's the most visible when two buttons in adjacent tiles have the same event number.

* Level 7: In the purple guard's room, I see you made the top floor shorter. Why?

Spoiler: show

To prevent this shortcut/skip; it is the only major DOS skip that it is still possible to do in this version.

For that it's enough to have the wall above the left gate (which you added).
If I add back the floor (to the fourth tile from right), the shortcut is still not possible, and it's still possible to climb up since there is space (one tile) between the floor and the wall.
Am I missing something?

On DOS though, none of the guards have voices.

Instead, the prince can scream when falling, which he doesn't do on the SNES.


EDIT:

Ha ha, you discovered it! Back when I was doing this, I was going to ask for a hack, but I figured this idea, and worked well enough.

I found another clever trick in your mod, on level 13.
There are hidden skeletons in the wall, who stand on buttons, which trigger the loose floors on the ceiling, so they fall when you enter the room.

[Shauing]

You got it, and the Level 9 one is also fixed by making the left switch also open the door next to it.

I didn't notice that in my playthrough; but now I checked it and it's indeed so.

Tried to fix as many softlocks as I could without changing the level/puzzle design, but not all of them were fixed.

Huh, thought this was a SNES bug, but I didn't know that it seems that if a trigger is shared, all the buttons with the same trigger will display the pressed graphic.

The same happens in the second room of level 9.

Actually the DOS version has this bug as well, but the other buttons with the same trigger are usually not redrawn immediately, so it's less visible.
It's the most visible when two buttons in adjacent tiles have the same event number.

Ah, I see. I checked if there were more as well, and only found the Level 9 one; I fixed all of those. I think my "The Queen Of Light" has a few of those trigger bugs as well.

* Level 7: In the purple guard's room, I see you made the top floor shorter. Why?

Spoiler: show

To prevent this shortcut/skip; it is the only major DOS skip that it is still possible to do in this version.

For that it's enough to have the wall above the left gate (which you added).
If I add back the floor (to the fourth tile from right), the shortcut is still not possible, and it's still possible to climb up since there is space (one tile) between the floor and the wall.
Am I missing something?

I wanted to maintain the two tile space between the wall and floor so it looked less obvious that I added that a wall. But yeah, probably it's a pointless change as I made the top floor shorter. I have added back the floor.

On DOS though, none of the guards have voices.

Instead, the prince can scream when falling, which he doesn't do on the SNES.

I wonder if, we can add this by adding an instruction that plays a new/existing music/sound cue pointer that uses one of the existing voice samples (like the amazon for example) and I write some pitch modification to recreate the falling scream. The amazon sample as used has some pitch bending to make it sound like a damage grunt.
The amazon voice sample seems to be the only one with specific looping so that it can sustain notes. We could do a falling Prince sound with it and insert it by replacing a music cue or where there is free space. Then, it's a matter to add an instruction to play this cue whenever the prince falls more than two tiles (if no specific height can be indicated, a rest (silence) that lasts that long could be specified as well).

EDIT:

Ha ha, you discovered it! Back when I was doing this, I was going to ask for a hack, but I figured this idea, and worked well enough.

I found another clever trick in your mod, on level 13.
There are hidden skeletons in the wall, who stand on buttons, which trigger the loose floors on the ceiling, so they fall when you enter the room.

Exactly. My original idea was that the Prince in his running entry would activate a button that triggered the loose floors, but I didn't want the button to be visible as the DOS does not show anything that triggers the loose tiles. So, hidden skeletons were used as they don't display a lifebar.

[Shauing]

On DOS though, none of the guards have voices.

Instead, the prince can scream when falling, which he doesn't do on the SNES.

Here's a test of a Prince scream while falling. I replaced a level music with the scream and added a small silence so that it starts a bit after the Prince falls more than two rows. As I am using the current level's music, the scream would play everytime the level music restarts (after a battle or drinking a potion for example). So, perhaps a hack similar to the ''At the start of Level 1'' should be created, so that this scream only plays when the Prince has fallen more than two rows.

[Shauing]

Spoiler: show

Here's a test of a Prince scream while falling. I replaced a level music with the scream and added a small silence so that it starts a bit after the Prince falls more than two rows. As I am using the current level's music, the scream would play everytime the level music restarts (after a battle or drinking a potion for example). So, perhaps a hack similar to the ''At the start of Level 1'' should be created, so that this scream only plays when the Prince has fallen more than two rows.

Honest opinion though, what do you think about this scream? It's good/okay enough? Shall it be different or perhaps avoid to insert it at all?

[Norbert]

Honest opinion though, what do you think about this scream? It's good/okay enough? Shall it be different or perhaps avoid to insert it at all?

IMO, certainly better to have this scream than no scream.
And in most cases the fall distance won't be as long, which will make it sound more natural.

[Shauing]

Spoiler: show

Honest opinion though, what do you think about this scream? It's good/okay enough? Shall it be different or perhaps avoid to insert it at all?

IMO, certainly better to have this scream than no scream.
And in most cases the fall distance won't be as long, which will make it sound more natural.

I can make it last just a second/second and-a half, instead of almost three seconds. I think the DOS scream also lasts only like almost two seconds. Still, I need a hack so that only plays the scream when the Prince has fallen (specifically, more than two tiles). And if I intend the scream to be a sound cue instead of a replaced music cue, the scream data might have to be written where there's free space, so the hack might have to be different.

By the way, when I was testing/playing with the sound effects written space, I couldn't found the Amazon's voice data, perhaps is located in a different place?

[David]

Still, I need a hack so that only plays the scream when the Prince has fallen (specifically, more than two tiles).

I'll look into this.

By the way, when I was testing/playing with the sound effects written space, I couldn't found the Amazon's voice data, perhaps is located in a different place?

The amazon's voice when hurt is stored as: T64V15@43O4D2P12#D5-BP0+C2C

[David]

Still, I need a hack so that only plays the scream when the Prince has fallen (specifically, more than two tiles).

At 0xA9B4 write: 20 30 FE

At 0xFE30 write: AD B8 02 D0 13 AD 5F 04 C9 1F 90 0C A9 yy A2 01 20 xx xx A9 01 8D B8 02 AD 59 04 60
Where:
* xx xx is either 3A C9 if you want to play a sound effect, or 4D EA if you want to play a music.
* yy is the ID of the sound effect or music to play.
You can find a list of sound effect IDs at the end of this post.
(And the list of music IDs can be found here.)

At 0xA9DD write: 20 10 FE
At 0xFE10 write: 8D 3A 05 A9 00 8D B8 02 60

At 0xAB09 write: 20 20 FE
At 0xFE20 write: 8D 5F 04 8D B8 02 60

List of sound effects:

Spoiler: show

Code: Select all

00: crusher
(01: unknown)
02: drink
03: gate opening
04: chomper closing
05: loose floor shakes
06: guillotine goes down
07: press (floor)button
08: spinning log
09: gate closing fast / level door closing
0A: bump into wall / hang against wall
0B: enter a teleport / kid killed by stars / potion of warp
0C: spikes come out
0D: level door opening
0E: footstep / grab / soft landing / step at edge / going up on exit door stairs / amazon coming?
0F: running jump
10: sword moving
11: sword vs. sword (guard parries kid's attack)
12: sword vs. sword (kid parries guard's attack)
13: medium land (lose 1 HP) / hard land (die) / kid/guard chomped / kid/skel crushed / kid burnt by fire / kid hit by log / skull falls on kid / kid killed by guillotine
14: guard pokes kid / cheat activated / monster hurts kid / hurt potion
15: kid pokes guard/monster/shadow
16: jump through mirror
(17: empty)
(18: unknown)
19: fire
1A: mouse squeaks (on button)
(1B: unknown)
1C: move in menu / select menu item / move in password
1D: menu appears / game paused
1E: menu disappears / good/bad password
1F: release (floor)button
20: loose floor breaks
21: gate closing slow
22: gate closed / level door stops after opening
23: kid falls into spikes
24: kid pokes amazon
25: chomper opening / guillotine goes up
26: "Press button to continue" message blinks
27: kid pokes skeleton / skeleton fell out of room
28: kid killed by magic ball
29: Jaffar holding magic ball
2A: Jaffar throwing magic ball
2B: conveyor belt
2C: kid pokes fat/knight
2D: kid pokes Jaffar
(2E: exists but is not played)
(2F-FE: does not exist)
FF: stop all sounds

(TODO: I should copy this list of sound effect IDs to some easily findable place, together with the list of music IDs?)

[Shauing]

Spoiler: show

By the way, when I was testing/playing with the sound effects written space, I couldn't found the Amazon's voice data, perhaps is located in a different place?

The amazon's voice when hurt is stored as: T64V15@43O4D2P12#D5-BP0+C2C

Argh, I confused myself. I meant the 11 bytes that describe the Amazon's voice. Like the instruments, there's 11 bytes below the sound effects written space, but I couldn't find the Amazon; I even did an attempt where I erased all 11 bytes and pretty much every sound effect bar the Amazon was muted though I attempted it today and now it is muted...huh.

[Shauing]

Spoiler: show

Still, I need a hack so that only plays the scream when the Prince has fallen (specifically, more than two tiles).

At 0xA9B4 write: 20 30 FE

At 0xFE30 write: AD B8 02 D0 13 AD 5F 04 C9 1F 90 0C A9 yy A2 01 20 xx xx A9 01 8D B8 02 AD 59 04 60
Where:
* xx xx is either 3A C9 if you want to play a sound effect, or 4D EA if you want to play a music.
* yy is the ID of the sound effect or music to play.
You can find a list of sound effect IDs at the end of this post.
(And the list of music IDs can be found here.)

At 0xA9DD write: 20 10 FE
At 0xFE10 write: 8D 3A 05 A9 00 8D B8 02 60

At 0xAB09 write: 20 20 FE
At 0xFE20 write: 8D 5F 04 8D B8 02 60

YES. And even I don't have to put a rest at the beginning to accommodate for the falling time. A curious nitpick is that, if the scream is a music cue and I go the pause menu when the screams starts to play, it will keep playing perhaps because it's a music cue.

List of sound effects:

Spoiler: show

Code: Select all

00: crusher
(01: unknown)
02: drink
03: gate opening
04: chomper closing
05: loose floor shakes
06: guillotine goes down
07: press (floor)button
08: spinning log
09: gate closing fast / level door closing
0A: bump into wall / hang against wall
0B: enter a teleport / kid killed by stars / potion of warp
0C: spikes come out
0D: level door opening
0E: footstep / grab / soft landing / step at edge / going up on exit door stairs / amazon coming?
0F: running jump
10: sword moving
11: sword vs. sword (guard parries kid's attack)
12: sword vs. sword (kid parries guard's attack)
13: medium land (lose 1 HP) / hard land (die) / kid/guard chomped / kid/skel crushed / kid burnt by fire / kid hit by log / skull falls on kid / kid killed by guillotine
14: guard pokes kid / cheat activated / monster hurts kid / hurt potion
15: kid pokes guard/monster/shadow
16: jump through mirror
(17: empty)
(18: unknown)
19: fire
1A: mouse squeaks (on button)
(1B: unknown)
1C: move in menu / select menu item / move in password
1D: menu appears / game paused
1E: menu disappears / good/bad password
1F: release (floor)button
20: loose floor breaks
21: gate closing slow
22: gate closed / level door stops after opening
23: kid falls into spikes
24: kid pokes amazon
25: chomper opening / guillotine goes up
26: "Press button to continue" message blinks
27: kid pokes skeleton / skeleton fell out of room
28: kid killed by magic ball
29: Jaffar holding magic ball
2A: Jaffar throwing magic ball
2B: conveyor belt
2C: kid pokes fat/knight
2D: kid pokes Jaffar
(2E: exists but is not played)
(2F-FE: does not exist)
FF: stop all sounds

(TODO: I should copy this list of sound effect IDs to some easily findable place, together with the list of music IDs?)

This really helps as I tried to document them all, but I did it by replacing a sample on a music cue, and I couldn't identify them all.
This gives me the idea to change the scream to a sound effect and replace one of the unused ones (for this mod), so that when pausing, the scream won't play until its unpaused.
I also did an instrument list, but a few instruments (mainly some Eastern ones) I cannot identify their name.
Perhaps they should be documented at the end of the SNES format document, separating the sound effects & voices and instruments.