Aw: Re: Re: [stella] Gunfight 2600: Final Release Version

Subject: Aw: Re: Re: [stella] Gunfight 2600: Final Release Version
From: cybergoth@xxxxxxxx
Date: Wed, 21 Nov 2001 18:24:49 +0100 (CET)
Hi Eckhard!

> > Rats! I knew I should've implemented those tests 
> > checking if the routine is still intact!
 
> That wouldn't have helped much. Eventually all checksumming
> mechanisms go to a point where they have to decide wether to
> branch into the main game loop or not. And this code can
> always be manipulated by hackers.

Well, what I wanted to do was something like that:

Replace:
RTS
With:
RoutineIntact  RTS

and on any point later I'd do something like

LDA #<RoutineIntact
CMP #RTS
BEQ fine
       bailout
fine

Again I'm sure that most readers _here_ could 
detect/remove this or similar.
But the casual graphics-hacker stands absolutely
no chance.

> > Apart from that it's good to know that everything works fine 
> > beyond that obstacle... :-)
 
> After actually playing the game a bit, it seems that the
> background in the PAL version is rather bright. It might just
> be my TV, but maybe you could try something a little darker
> before releasing the game?

Ok, I'll do that.
 
> > As for the "hacking prevention code": That really is exactly what 
> > it is intended to be. 
> 
> > Of course I'm aware that anybody on this list is able to remove 
> > that code in next to no time, but I'm sure it prevents 99%
> > of the editgfx users from turning my cowboys into Bin Ladens... :-)
 
> I don't know, but after you have posted all the almost
> finished beta versions here this seems pretty pointless.
> Anyone who really wanted to hack your game without your
> permission could just use a beta version and get almost
> the same result.

Well, you're right. But then these 'Kabul' hacks 
didn't emerge before the WTC desaster...

Apart from that, I sure that people _here_ won't
missuse any old BINs for hacks.
And one needs to have public betas anyway.

And then there's always a difference between _any_ beta and
_the_ final version :-)
 
> > Do you know where and why the checksum differs?
> It seems that both the Cuttle Cart loading routine and the
> modified 7800 BIOS start the game with the carry bit being
> high. I don't know how it is on a normal 2600/7800 though.
> Maybe the 6502 starts up with the carry being low, but at
> least on the 7800 with it's BIOS, it might get changed to
> high as well.

Aha. Good to know.

Greetings,
     Manuel


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