Cheat Engine

Attack · Posted: Thu May 09, 2013 5:49 pm Post subject: Game timer

Hi, I am playing DLC Quest at the moment and there are some achievements for beating the game under certain times. I am about 5-10 minutes off. Open CE, but I cannot for the life of me figure out how to get the times. Tried searching for individual values, added up, unknown increasing/decreasing. So I really don't know where to go from there.

jucce · Posted: Fri May 10, 2013 2:16 pm Post subject: Re: Game timer

Attack · Posted: Fri May 10, 2013 2:19 pm Post subject:

Yes, there is a visible counter. I have figured out that I was approaching it very, very wrong.

Using the save game I can find the stored time. I can search for that value after I load the game. From there it's pointers, but I haven't used CE since Civ 5 came out, so it will take a lot of time before I can figure this out again

EDIT: OK, so maybe someone can help me, because I have become lost.

So the save file stores the time in millionth of a second... yeah. So for example, I open the save file and find this number: 6658500947, i.e. 11m5s...
Now I can find this number, but it's static. It is accessed to calculate the ongoing time as a base. So I can change it to 0, but that does not stop the time running. I can alter it up and down, but that doesn't help my cause.
The on going timer that uses this as a base, cannot be found, so there is some code, somewhere that I need to find
Only thing I can do is check what accesses the value, there are two lines
mov eax,[ecx]
mov edx,[ecx+04]
ecx being the address to my value. I don't even recognise any of this anymore. The tutorials are honestly not helping as they always deal with write access, not read.
Now I can save and quit to see some ore instructions, but that is no good, as they are then gone.

How do I go about tracing eax or edx further to hopefully find where the increasing counter is coming from so I can freeze or remove it?

jucce · Posted: Sat May 11, 2013 1:03 pm Post subject:

What if you edit the value in the save game? Subtract a couple of minutes then completing it under the time limit should be easy.

Alternatively hit "Show disassembler" when you have the code lines that access the value selected, then try to follow the code and see what happens with the base time.

You can also try replacing those two lines with "nop", reloading the save and hope that you will now start from a lower base. It's also possible to use code injection to change the base before it is read.

Attack · Posted: Sat May 11, 2013 2:21 pm Post subject:

It tracks the time from a new game. A save doesn't work as it has to be in one session

Gniarf · Posted: Sat May 11, 2013 3:57 pm Post subject:

Did you try the following theory: the game uses 2 variables to store the time. One stores the number of seconds (or mili/micro seconds) and one stores the number of minutes. That would defeat increased/decreased/not changed searches if you're not careful because the second counter is reset every minute.
So the idea would be new game, unknown value, wait 1mn 10s, increased value (by 1?), wait 30s, unchanged....

And another possibility is an encrypted timer, in which case just use the changed/unchanged filtering methods.

And yet another one, since you have to play in one session, is that they store only the start time, and repeatedly compute now-start_time.