Development:

1 - Game idea!
2 - Let's put some work in it!
3 - Let's store that data somewhere : Possible leak 1
4 - Let's outsource our work! : Possible leak 2
5 - The game is gold! I present to you this ISO : Possible leak 3
6 - Let's ship the gold dics to the presser : Possible leak 4
7 - At the presser : Possible leak 5
8 - Ship back to Quality Control : Possible leak 6
9 - Marketing shows off to select crowd : Possible leak 7
10 - Game is put in stores : Possibel leak 8

The possible leaks explained:

1 : Someone hacks the server
2 : TCP/IP capturing
3 : ISO's are kept somewhere, someone hacks the server (Again)
4 : Shipment involves people, who can steal packages or copy them
5 : Pressing manufacturing involves people , etc. See 4
6 : See 4
7 : Selected crowd writes down information and hacks it
8 : Store droid grabs the package, rips it and puts it on the nt

Now, how on earth to these m@d l33t warez distributors do it?

They got people at several places, usually at leak #8, but sometimes at #4 and THAT's why it's always a couple of weeks in advance.