[KaktoR]

Yes you can use 4x4:lzma. But you can also use lolz or some other.

Make a simple test with a sample file from that game (a file with about 500mb should do it).

First go with xtool+srep+4x4:lzma
Second go with xtool+srep+lolz

Both methods with the same file. Then look at ratio and speed and you can do a bit math more or less (extrapolation).