Metroid Prime: Federation Force Save Editing

Discussion in '3DS - ROM Hacking, Translations and Utilities' started by Blundermann, Aug 20, 2016.

  1. Blundermann
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    Blundermann GBAtemp Regular

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    I'm trying to figure out how to edit the save file for this game.
    It's a lot simpler than most of the save files I've seen. It only has one file, named "profileX.sav" (where X is the number of the profile; 1, 2, or 3)

    I've tried to edit my save to have all skins unlocked. I had two skins, so I assumed that this was where the skin unlocked data was, because there are two 01s in this string of FFs.

    [​IMG]

    However, if I change any of the FFs to 01s, it fails to load the save file with this error:

    [​IMG]

    Can anyone figure out if anything can be edited without it failing to load?
     
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  2. zoogie

    zoogie simple pimp tool

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    You need to find the checksums and patch those.
     
  3. Blundermann
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    Blundermann GBAtemp Regular

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    I assumed there would be some sort of integrity check in the save file, I just don't know where it is.
     
  4. zoogie

    zoogie simple pimp tool

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    Make a copy of a save then change something small in game. Usually just re-saving after a short time will do it or editing something in the options, lol.
    Then look for a 2-4 byte random number in the save file (usually at the beginning or end) to change completely between saves. That should be the checksum.
    You then have to figure out what type of checksum it is (usually crc16 or crc32) and what range of the save it covers.

    I don't know if that's a good explanation, but it's the best I can do for now.
     
    Last edited by zoogie, Aug 20, 2016
  5. Pecrow

    Pecrow GBAtemp Maniac

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    Interested in this too :-)
     
  6. Blundermann
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    Blundermann GBAtemp Regular

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    Your explanation was just fine. I very much appreciate it.

    I believe there is one four-byte checksum that resides at the top of the file at 0x00.

    Save 1:
    [​IMG]
    Save 2:
    [​IMG]
    Save 3:
    [​IMG]
    Save 4:
    [​IMG]

    Notice that bytes 0x04 through 0x07, and 0x09 remain unchanged through the four files.
    Not sure, but I think the changing value at 0x08 might be a record of when the save was recorded.

    Would it be easier to figure out how the game generates its checksum value, or to patch out the game's save integrity check entirely using NTR or something?
     
    Last edited by Blundermann, Aug 20, 2016
  7. zoogie

    zoogie simple pimp tool

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    It's definitely just easier to patch the correct crc32 every time you change something in the save. You just need to experiment what range the crc covers, then test it against what the game wrote at 0x0. HxD has a checksum option in its menu that can check a highlighted area.

    edit: almost forgot, be aware that the crc32 will likely be stored in reverse byte order since it's little endian.
     
    Last edited by zoogie, Aug 20, 2016
  8. Chris_Highwind

    Chris_Highwind GBAtemp Fan

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    Weird, I was half expecting the hacking scene to pretend this game doesn't exist, considering everyone considers Federation Force to be a worse game than Other M for completely petty reasons.
     
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  9. ShadowOne333

    ShadowOne333 GBAtemp Guru

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    The only thing I want the hacking scene to do to this game is to hack the models of all the in game characters to make them have proper body proportions.
    I despise those stupid big heads in each and every single one of the models.

    If the game had character models with proper body proportions I can guarantee you that it wouldn't have that much of a negative impact in the overall series for a spinoff.
     
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  10. SirBeethoven

    SirBeethoven 3.145.... something. E=mc2

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    Awesome!! I'm interested!!
     
  11. Blundermann
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    Blundermann GBAtemp Regular

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    I got the game as soon as it came out, and I've poured hours into it already. I absolutely fucking love it. The body proportions are stupid, but IMO it doesn't matter when the gameplay is as polished as it is.

    I've never played Other M, so I can't make any comparisons to it, but Federation Force definitely inspired me to poke around with its save data, because I enjoyed playing the game so much. If everyone else is going to pretend it doesn't exist, that's fine, but this thread is for those that want to acknowledge it.
     
    Last edited by Blundermann, Aug 21, 2016
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  12. RemixDeluxe

    RemixDeluxe GBAtemp Psycho!

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    I was hoping for something along the lines of an NTR plugin to get all the mods, skins, and possibly infinite missiles, etc.
     
  13. Salvador Gremory

    Salvador Gremory Newbie

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    in SpeedFly upload it yesterday
     
  14. RemixDeluxe

    RemixDeluxe GBAtemp Psycho!

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    A link would be nice thank you
     
  15. N7Kopper

    N7Kopper Proud lover of a three-inch girlfriend

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    I'm assuming that the perpetual big head mode is for some kind of gameplay reason. Visibility, most likely.

    This game's good. I don't care how butthurt people are that you don't play as Samus. That said - interquel/DLC where you play Samus' side of the story when?
     
  16. Blundermann
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    Blundermann GBAtemp Regular

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    Last edited by Blundermann, Aug 26, 2016
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  17. RemixDeluxe

    RemixDeluxe GBAtemp Psycho!

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    I used my amiiqo to unlock the Samus and Zero Suit Samus paint jobs, but when I used Bowser (super smash), Bowser Jr., and Mario (super smash) I got X ray 3 times in a row. Do all the other amiibo just give X-ray or is there something I'm missing?
     
  18. Nisky808

    Nisky808 Member

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    The Mario skins are Blast Ball only.
     
  19. RemixDeluxe

    RemixDeluxe GBAtemp Psycho!

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    That doesn't really answer my question though. I unlocked the same skin 3 times in a row using 3 different amiibo, I'm just trying to figure out what the specifics are to their unlocking.
     
  20. Chris_Highwind

    Chris_Highwind GBAtemp Fan

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