You can pretty much get all the games via Steam illegally. Only thing is Multiplayer is only possible via a VPN like Hamachi or just playing on a Cracked Server.
You don't even need steam, all you need is the gcf and ncf files if any and use a steam emulator and your good to go.
Getting a title before the official release data while it's on preload encryption i'm not sure. I've seen a couple of "encrypted" titles fully unpacked before the release, so it might not be as hard as imagined.