Imperium Galactum

Talk about everything related to general reverse engineering of computer games!

Moderator: Kroah

Imperium Galactum

Postby jaybird3rd » 05 Dec 2013, 21:27

Hello, Kroah:

First of all, thanks for setting up this Web site and forum! I'm impressed at the number of games you've reverse-engineered, and as someone who has been playing many of them (on the Atari 800) for years, I'm looking forward to getting to know them even better now by studying the code!

I was reading through this forum thread on AtariAge from about a year ago ...

http://atariage.com/forums/topic/200885-need-info-about-the-abc-basic-compiler-from-monarch-data-systems/

... and you mentioned that you were working at the time on reverse-engineering Imperium Galactum for the Atari 800. By any chance, did you ever complete your work on this title? I'm a homebrew developer who is interested in creating a version of Imperium Galactum for another platform, and I'd be very interested to see your decompiled code for this title, if you have it.

Thanks again for your consideration!
jaybird3rd
 
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Joined: 05 Dec 2013, 21:20

Re: Imperium Galactum

Postby Kroah » 15 Dec 2013, 02:52

Hello Jaybird,

First of all, thanks for setting up this Web site and forum! I'm impressed at the number of games you've reverse-engineered, and as someone who has been playing many of them (on the Atari 800) for years, I'm looking forward to getting to know them even better now by studying the code!

Thanks for your kind words. I see you have grown up an Atari in the hands, with the tools we have today, it's really easy to dig in the asm code to understand the inner working of the games.

... and you mentioned that you were working at the time on reverse-engineering Imperium Galactum for the Atari 800. By any chance, did you ever complete your work on this title?

Imperium Galactum is not an easy task. Like you have read on Atariage, this game is compiled with the ABC compiler.
With the help of Thomas Richter, i was able to decompile the "compiled Basic" part of the game.
But... Imperium Galactum uses many inline call to assembly code (this one, pure 6502 code) to speed up core routines.
Unfortunately, those routines aren't only graphic/display code (which would be easy to disassemble), but are mainly AI routines which are awful to understand.
On top of that, variables aren't passed by arguments between the basic and 6502 code : all the variables are global and are shared using many peek/poke...
And to definitively kill my motivation, instead of 1 main Basic program, there are one for each phase, where each variable must be discovered again.
In fact, it's not impossible, but it requires a lot of time (too much for me).

I can still send you my work in progress but you will need some knowledge to reverse the 6502 AI with IDA (and Visual Studio Express C#).
(I would want to finish the First Samurai viewer before, so i will not be able to do this before 2014).
Kroah
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Location: France

Re: Imperium Galactum

Postby jaybird3rd » 27 Mar 2014, 22:05

This is a VERY belated follow-up, but I just wanted to say thanks for posting your decompiler code and Imperium Galactum WIP on AtariAge. I'll be interested to look it over when I have the chance!
jaybird3rd
 
Posts: 2
Joined: 05 Dec 2013, 21:20


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