Hello, I am yet another newbie prostrating myself before the alter of knowledge

Anyway, I've been doing my research, getting my feet wet and I think I have a reasonable understanding of the processes as far as a newbie can be.
So as it stands, I understand that some of the games I may want to repack, require unpacking and to do this, I need to find out what form of compression was initially used.
In one particular case, I found that a game uses some form of ARC compression but it seems to be custom on that particular game. Is there a way of overcoming forms of custom compression in order to unpack files from a .bin? Am I sniffing up the wrong tree?
Thanks in advance for any clarity on this.