normally its down to the talent of the developers to how small they can compress the game down into. oblivion which most consider an epic game had no prerendered cut scenes as everything was in game, but it had alot of voice acting and it was a massive world (26sq miles). Yet IIRC it only took up 4GB of disc space. This was down to Bethesda developing better compression techniques specifically for this game otherwise it would not have fit. In the right hands almost any game can be compressed down to size without loss in quality. MGS4 may be an exception to this due to the huge volume of prerendered cut scenes it will have as all MGS games have had. MGS1 or 2 came on more than one disc, i know at least one of them did because i can remember having to switch over whilst playing.
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your right blue dragon did use up 3 discs.
normally its down to the talent of the developers to how small they can compress the game down into. oblivion which most consider an epic game had no prerendered cut scenes as everything was in game, but it had alot of voice acting and it was a massive world (26sq miles). Yet IIRC it only took up 4GB of disc space. This was down to Bethesda developing better compression techniques specifically for this game otherwise it would not have fit. In the right hands almost any game can be compressed down to size without loss in quality. MGS4 may be an exception to this due to the huge volume of prerendered cut scenes it will have as all MGS games have had. MGS1 or 2 came on more than one disc, i know at least one of them did because i can remember having to switch over whilst playing.