Having said that, because PC games install everything to the HDD, and rely on the DVD as merely a disc check mechanism (if that, now) PC games can run some serious compression mechanisms on the install discs. You couldn't do the same on the 360 or PS3 as they'd spend too much time decompressing files to do anything else.
Indeed, I was saving that point! ;)
Compression algorithms have gotten really really good. I mean Portal 2 is some 12 GB installed for example and it's certainly not pushing the envelope.
Also Yeah I guess there was two copies of Far Cry, the 5 CD version and a single DVD version.
http://www.gameskb.com/Uwe/Forum.aspx/pc-games-action/3254/Far-Cry-how-many-install-CDs-5
The problem with basically every single game released on multiple DVD's on the 360 is that none of them are on the PC I don't believe.
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To jump back to Blu-ray Drives (not game disks!) not picking up steam in computers, That's another problem. It's a chicken and egg thing. There isn't much of a reason to ship a game on Blu-Ray if less than what? 25%? 15%? 10%? 5%? of people have a Blu-Ray reader in their PC.
The fact that most of people don't is a separate problem stemming from a few problems. CD's and DVD's were often used to store Data, how many people do you know that store data on Blu-Ray disks? A 16 or 32GB thumb drive and free falling hard disk drive prices have eliminated the need for burning Optical Media. The other big problem that PS mentioned is that support for Blu-Ray is really piss poor. Can you even play Blu-Ray movies on OSX yet? Playing on linux is non trivial. et cetera