How to get Massive Compression?

[Megalexxx]

I think you don't understand...

Dummy files don't shrink anything ! They are used for other purpose.
You can't get incredible compression if your original files are big.

The game you had, that was 30 Mb compressed and 650 Mb uncompressed had a dummy file, BUT it also was very small before compression !!!
To simplify, a dummy file is a huge file filled with "0". If you don't compress it, you'll have (say) 640.000.000 X "0" (so 640.000.000 bytes). Once compressed, it will be something like a very few bytes : some to say your original file had 640.000.000 times the same caracter, and some the code the caracter.

BUT, a dummy file won't affect in any way the compressed size of the other files !