Also even if Runey change the compression and use a more efficient one, it would only help for a short time. Size of the game would go down, but with his ongoing work and expansion of Harem Hotel, the size will go up again.
Not saying that this is useless, but that the help of this is limited for the whole game.
From patch point view, the archive.rpa file use a lot of space around 300 MB of the patch size of 1100 MB. I don't know what is in this archive.rpa file. Yet, if some 3rd party tool would be used that can make updates on sublevel file, it could save space even for the patches (also can sort out the need to manual delete of old files...).
One other possible solution - thinking loud - would be to use the Harem Hotel game itself and put an update mechanism in it. I know that at least on other game is doing this, although I don't know how they doing it.