• The files are MHEG5 (red button) ASN1.
• This can be used to convert the to a human readable format.
• Use these instructions to play the files (after replacing your a file with theirs).
• The extras menu seems to allow us to input a flag. It displays red for incorrect.
• Searching for green RGB (=00=FF=00=00) brings us to link 2584.
• Link 2584 is called from link 117 which seems to be the flag checking logic.
• In short, the logic is:
  • Shift var_51 based on the length of the inputted flag to make var_65.
  • Convert the inputted flag to binary (7 bits per char, using the var_49 charset).
  • XOR var_65 with the binary flag (result stored in var_70).
  • Compare var_70 to var_62.
• Things that helped in reversing:
  • The player variable view.
  • Take the first argument of :Call (e.g. 27), look at the top of the file for the corresponding string (e.g. GSL), and then search that in the spec. I think second argument is maybe a Boolean of if the call is made, after that it is the spec arguments.
  • Link blocks often have an :EventData boolean at the start. This seems to determine if they are executed (based on a proceeding :TestVariable).
• Solve script:

def xor(a, b):
    return "".join(str(int(a_ != b_)) for a_, b_ in zip(a, b))


var_51 = "00011001101110001010100100010001100100011001000011010001110101001111011011000100100111100100001011000010111001110101101110101100100101111010001100011110010111000010010100111100111101111011110100111010010110011010111110110111010111100100011110011100000010010100110100000110101011110101001010000010101000101001001010010111101110111110011001010100010000000110100001110100101111110100110011011100100000011011010101011110010010111111011101001111000100001101101001011000000001111110"
var_52 = "11010011010000101111101110101001011001101100101000111101101110101101010000010111101110000110100001000111101100000001110010010000000001011111001101111110011110111100111000111111101000110110010111100111110001111010110100110111000001001111010001100110111000101010010001000110010001100100001101000111010100111101101100010010011110010000101100001011100111010110111010110010010111101000110001111001011100001001010011110011110111101111010011101001011001101011111011011101011110010001"
charset = "1234567890qwertyuiopasdfghjkl{zxcvbnm_!@#$%^&*+=QWERTYUIOPASDFGHJKL}ZXCVBNM-"  # =3D is = escaped


for flag_length in range(9, 49):
    var_65 = var_51[7 * flag_length :] + var_51[: 7 * flag_length]
    flag_bin = xor(var_52, var_65)

    flag = ""

    try:
        for i in range(0, flag_length * 7, 7):
            flag_char = int(flag_bin[i : i + 7], 2)
            flag += charset[flag_char]
    except IndexError:
        pass

    print(flag)