Tutorial #4
Davids BackGammon v2.6.3
(c) David Byrum
http://members.aol.com/wingammon/backgammon
by AlpHaz


This tutorial will guide you in the way to be able to play the good game of Backgammon. This game has some limitations and we are not allowed to finnish a whole game.

First take a backup and disassemble the orginal file. When it is complete push the Str_Ref button and look for some interesting Strings. 
We collect some strings in a table and then take some actions.

"Incorrect Password"

"Please send nothing. I already "
"have a registered copy of the "
"game."

"Not Available in the demo version"

"Password is Correct"

"Registered"
"Demo"


We take the BAD/GOOD thing first. Lets check the Incorrect string first. This is how it look:

:00421C27 57                      push edi
:00421C28 E8935DFEFF              call 004079C0
:00421C2D 83C40C                  add esp, 0000000C
:00421C30 84C0                    test al, al
:00421C32 0F847F030000            je 00421FB7
:00421C38 56                      push esi

* Possible StringData Ref from Data Obj ->"Incorrect Password"
                                  |
:00421C39 BE6CAA4700              mov esi, 0047AA6C
:00421C3E 8DBDD4FEFFFF            lea edi, dword ptr [ebp+FFFFFED4]

Now you know what to change, so lets do that.
Lets try it to see if it works now. No, it doesn't. Ok. Go back and hit the other location. Here:

:00421FC7 E8255AFEFF              call 004079F1
:00421FCC 83C40C                  add esp, 0000000C
:00421FCF 84C0                    test al, al
:00421FD1 0F847F030000            je 00422356
:00421FD7 56                      push esi

* Possible StringData Ref from Data Obj ->"Incorrect Password"
                                  |
:00421FD8 BEE4AA4700              mov esi, 0047AAE4
:00421FDD 8DBD3CFEFFFF            lea edi, dword ptr [ebp+FFFFFE3C]

As you see, you land here by the first Jump. Well lets change the Jump here too..


Next, check if the program works good. No, not yet. But we know what we are doing here, so lets continue.