Loaded game files.

[Lain Ai]

Hi, basically I've run out of ideas on something I'm working on. I usually don't like to ask for help but I'm not sure what to look for now.

Basically how do programs/games load files. Let's say a game needs XXX file for configuration how does it load it. The game in question loads a file I'd like to modify, but the problem is they check the files physical data (MD5 I assume, not sure they're very vague on it.) and if it matches it's good, if not they basically lock you out of accessing it. So basically I want to insert my file in place of it. Now I've tried just changing the location in the memory and reloading but since the file it loads is a compressed file it ends up just not working. I guess I need to elaborate a bit.

Game > Compressed file > Multiple files in it.
I need to change one file inside it.

I can modify the compressed file and change what I need. But the game would detect this, the detection method they use is actually a DLL they load. The DLL is necessary as it also does some other important stuff or I'd just re-write it.

Okay so basically, is there anyway I can change the actual way the program loads the file, possibly by API hooking with DLL injection? Any ideas? Sorry If I rambled it's really confusing since there's so much to it.

Edit: lol. In my own posting of this I got an idea to try and modify the game itself to see if I can find where it decides what file to load. Wish me luck.