Phantasy Star III speed hack

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Phantasy Star III speed hack

Postby Tryphon » Fri Oct 25, 2013 9:33 pm

I remember having seen one of these but it was buggy. So I looked into the ROM.

I have no time to fully test it, but I played in Landen village and castle, it seemed to work. If you could give me feedbacks, it'd be nice.

I suppose it's not legible to post ROM files, so here's how to do yours :

- open the ROM with an hex editor (I use MadEdit or HxD)
- at offset 3036, put 54 (all is hexadecimal)
- at offset 2E1D : put 02
- at offset 4E4C to 4E53 : put 00 FE 02 00 00 02 FE 00

Et voilà ! Normally the party is now twice faster. I'd be interested by knowing if it works when you have several members in your team.

Edit : I didn't fix the checksum, so disable checksum checking in your emulator (most of them don't check checksums anyway)
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Joined: Wed Mar 28, 2012 11:29 pm

Re: Phantasy Star III speed hack

Postby Tryphon » Tue Oct 29, 2013 11:07 pm

Not much success.

Let's try more : this IPS patch allows you to move in all eight directions, at double speed. The gameplay is now similar to Phantasy Star Generations remakes.

So no more "The game is too slow" complains (I agree, many more complains remains).

Additionnal infos :

- The base ROM is "Phantasy Star 3 - Generations of Doom (UE) [!].bin"

- You'll find in the archive the ips file, and the sources (the asm file and the python script I used to patch the ROM, they are useless unless you want to incorporate the patch to another patched version)

- I didn't edit the ROM header, so you can expect a weird message from your emulator, and it may prevent the game from being launched on a real Genesis. If the crowd shouts my name with passion I'll add it, but I'd be surprised...

- I deleted the checksum verification subroutine, so the patch works on any emulator (tested with Fusion, Gens, Regen and Exodus)

- You will notice some artifacts when going diagonally through a door. They are due to two things : 1) the fading to black is now too slow compared to the team speed (I may fix that) and 2) the collision maps weren't studied for diagonal moves. None of them alter the game.

- Your savestates from unpatched version will behave strangely when loading : the scrolling will be slower than the team, and the collisions will be wrong. Everything will be back to normal as soon as you'll have left the current map (simply exit / reenter in the town for example)

- this patch may not work with other patched versions, if the script has been expanded for example. I expanded the ROM (from address 0xC0000) to put my modified routines, maybe other patchs did the same. It's quite simple to adapt it if needed, just ask.

- the patch doesn't modify the other ways of moving, e.g. when sailing a boat, or Wren's transformations. It's not so important since the game is already fast in those situations. I'd have liked to implement diagonal moves there, but none of the emulator I used for this hack can load gsx savestates...

I hope some people will enjoy this patch :whistle:
Phantasy Star 3
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