A few things:
- PC games have become very difficult to reverse-engineer. So many cards and so many configurations. Reverse-engineering DirectX is not a cakewalk, either. .Net is a little simpler, as is Java, because in those cases the code is naught but operations and interface calls (which are akin to the BIOS of yore).
- Fortunately, data compression on PC is nearly non-existant. Files may be archived and the files themselves may be in compressed formats, but actual compression of text is rare. You should be able to find what you're looking for with a hex editor. You should be able to deduce the compression format by looking at the start of the file. From there find a compressor for the attendant formats and decompress the data. Sometimes it's right out in the open. In Java, the format is always JAR, which you can open with WinRAR, probably.