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(GG) Sonic 2 Auto Demo Prototype (1991-12-05) - Info & Download

Discussion in 'General Sonic Discussion' started by Orengefox, Aug 20, 2014.

  1. Captain VG

    Captain VG

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    Walked left at the start and suddenly everything stopped functioning :V

    Edit: hahah reaching the end and continuing to the right produces the same effect. its like the collision detaches from the sprites.
     
  2. Mastered Realm

    Mastered Realm

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    Heey!

    [​IMG]

    [​IMG]
     
  3. Yuski

    Yuski

    Dragons, dragons everywhere! Oldbie
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    To make Sonic roll, you don't need to run then press down, just hold down and press left or right and he'll spin.

    Really buggy!
     
  4. MarkeyJester

    MarkeyJester

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    Here's one for you, using that ROM I linked, the bytes at offset 054B and 0550 decide the zone/act, by default they are set to 00 and 00 (Zone 0 act 0). Change them so see the other levels.

    Here's a tool to help those who don't use hexadecimal editors but wish to take a look at the other acts/zones. Just drag and drop the autodemo ROM onto the application (On the file, not the console window) and then type in the Zone and Act ID's to patch onto the ROM.
     
  5. You-Are-Pwned

    You-Are-Pwned

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    How did you discover those thing so fast? I'm interested in what kind of debugger of SMS or Z80 you use, if any.

    EDIT: It looks like those are the values for all 3 levels: (Zone 0 Act 0), (Zone 1 Act 2) and (Zone 3 Act 1) respectively.
    First level:
    Code (Text):
    1.  
    2. ROM:054A                 ld      a, 0
    3. ROM:054C                 ld      (byte_D287), a
    4. ROM:054F                 ld      a, 0
    5. ROM:0551                 ld      (byte_D288), a
    6. ROM:0554                 call    sub_734
    Second level:
    Code (Text):
    1.  
    2. ROM:05AA                 ld      a, 1
    3. ROM:05AC                 ld      (byte_D287), a
    4. ROM:05AF                 ld      a, 2
    5. ROM:05B1                 ld      (byte_D288), a
    6. ROM:05B4                 call    sub_734
    Third level:
    Code (Text):
    1.  
    2. ROM:0602                 ld      a, 3
    3. ROM:0604                 ld      (byte_D287), a
    4. ROM:0607                 ld      a, 1
    5. ROM:0609                 ld      (byte_D288), a
    6. ROM:060C                 call    sub_734
     
  6. Mastered Realm

    Mastered Realm

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    Holy shit

    [​IMG]
     
  7. You-Are-Pwned

    You-Are-Pwned

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    There seems to be more levels than just three though... A lot of them are unfinished.
     
  8. doc eggfan

    doc eggfan

    Are you pondering what I'm pondering? Wiki Sysop
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    GreatMegaLD, GreatSC3k, Great SG1k
    O_O

    I remember finding those unused tiles wayback when. Nice to see them arranged as intended.
     
  9. DustArma

    DustArma

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    Learning Python.
    The autodemo is so ridiculously broken, it makes Sonic Crackers look finished.
     
  10. Dark Sonic

    Dark Sonic

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    Wow what a mess, it's wonderful :specialed:
     
  11. Mastered Realm

    Mastered Realm

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    Why did they remove this?

    ;-;

    [​IMG]
     
  12. doc eggfan

    doc eggfan

    Are you pondering what I'm pondering? Wiki Sysop
    9,750
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    ACT
    GreatMegaLD, GreatSC3k, Great SG1k
    !0_0!

    I thought those unused tiles were for a loop.
     
  13. steveswede

    steveswede

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    Just a question guys, why do the 8 bit SMS games have enormous borders
     
  14. nineko

    nineko

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    It's not fair, I couldn't take a deep look at this until now, and the song has already been discovered, I feel useless :(
     
  15. Mastered Realm

    Mastered Realm

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    To edit the ROM, just use Meka. It has a realtime ROM editor :)
     
  16. Ravenfreak

    Ravenfreak

    Feeling festive this year Tech Member
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    I disassembled the ROM myself. :v: But it looks like MJ beat me to unlocking the controls and the level/act values. xP Still going to mess around with this, and explore the levels. :v:
     
  17. nineko

    nineko

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    Yeah I could find the song into the ROM and I was about to port it to the final version of Sonic 2 but I guess there's no point into doing that anymore :(

    I hate my timezone.
     
  18. MarkeyJester

    MarkeyJester

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    Oh do so! I mean geez, the more people having a look, the better...

    I'm also pretty damn hyped with Master Emerald's findings, they seem to fill an empty picture quite well.

    [​IMG]

    Combined with experience and understanding of Z80 binary instructions, and how games function on the old consoles! It seems like a drag all these years, but I'm actually rather glad in the end.
     
  19. Captain VG

    Captain VG

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    So I tried a bit of an experiment and tried load Zone 2 Act 3 (Sky High). It ended up loading Zone 3 Act 0, the removed act from Underground except it did not load with the mine cart...
     
  20. Xilla

    Xilla

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    Tried some random zone and act values and ended up in a horrendously broken (even more so than usual) GHZ with what looks like a massively oversized (and non-functioning) bridge.