The Xbox 360 comes out in 3 months and so far it is planned to ship with a standard DVD drive. It's simple math why this is a problem.
Let's take the transition from PS1 to PS2. PS1 characters were generally 200 to 1500 polygons max. PS2 characters are generally 1500 to 15000 polygons. That 7 to ten times the polygons. A PS1 only had 3.5 meg of ram. A PS2 has 40meg of ram. That's nearly 10 times the ram. These types of facts generally translate into 10 times the data on the DVD.
So now, with the next gen coming up the new systems both appear to have 512meg of ram. That's 8 times more than Xbox and 12 times more than PS2. So, if we calculate it out, if the data being used is going to go up by 8 to 12 times then if the average game uses a one gig of data that becomes 8 to 12 gigs needed on the DVD. DVDs only store 4.7 gigs of data. That doesn't even count for bigger games like Grand Theft Auto, Gran Turismo, Jak & Daxter, Ratchet & Clank, God of War and any others that probably use 3 gig or more of a DVD just for game data (not for audio and not for movies). Put those games on the next gen and with all the fancy textures, normal maps, gloss maps, HDR environment maps, and high res polygon models they will not fit on a DVD and we haven't even considered adding HD video which Mr. Allard emphasised so much in past 360 presentations.
Checking out some current gen games to see how much data they use. (note, these are guesses looking at the contents of the DVDs)
|Burnout 3 XBox:||Burnout 3 Next Gen:|
|Video:||0.3gig||0.3gig ?? to make it HDTV?|
|Data:||0.65gig||0.65gig 8 <-> 12 = 5.2gig <-> 7.8gig|
|Total space:||2.3gig||6.85gig <-> 9.45gig not including HD video|
|Halo 2 XBox:||Halo 2: Next Gen|
|Video:||0.4 gig||0.4 gig ?? to make it HDTV|
|Data:||4.4 gig||4.4 gig 8 <-> 12 = 35.2gig <-> 52.8gig|
|Total space:||4.8gig||35.6gig to 53.2gig not including HD video|
Pandora Tomorrow XBox:
Pandora Tomorrow Next Gen:
|Video:||1.5gig||1.5gig ?? to make it HDTV|
|Data:||0.7gig||0.7gig 8 <-> 12 = 5.6gig <-> 8.4gig|
|Total space:||2.6gig||7.5gig <-> 10.3gig not including HD video|
|Jak 3 PS2:||Jak 3 Next Gen:|
|Data:||0.9gig||0.9gig 8 <-> 12 = 7.2gig <-> 10.8gig|
|Total space:||4.1gig||10.4gig <-> 14gig|
|GTA:SA PS2:||GTA:SA Next Gen:|
|Data:||1.4gig||1.4gig 8 <-> 12 = 11.2gig <-> 16.8gig|
|Total space:||3.9gig||14gig <-> 19.6gig|
Is this an over simplification, yes but it's not that far off the mark. To give a very concrete example, Tim Sweeney of Unreal fame told us that a single character in Gears of War uses a 2048x2048 texture. Given that next gen characters need at least a color map and a normal/height map a 2048x2048 texture is 32MEG just for the texture of one single character. Nearly the entire memory of a PS2 or 1/2 the memory of an XBox just to texture one single character. Yes, you can compress the texture, you could also compress the texture on the old systems too. The point is even if you compress them their relative sizes are still going to be 8x to 12x in size which means the data is going to grow 8 to 12 times.
Some people will mention not all data is graphic and the non−graphic data will not expand as much. First off, it is still likely to expand. Maybe not 8−12x but more physics, more real world attributes like friction per polygon etc or more A.I. info will increase non graphic data as well but even so, non−graphic data is insignificant in size compared with graphic data. Do you think a 100 artists on a giant EA team are making non−graphic data? No, they are making graphics and those graphics are going to take 8−12x the space on next gen. At best you could probably take those data numbers above and split them 80% graphics 20% non−graphics (probably more like 90%, 10%) then multiply only the graphic piece by 8 to 12. You'll still see they don't fit on a DVD.
So, what does this tell us? 360 without HD−DVD is screwed! Sure the developers will make games for it but there is clearly a limit. Many current gen games converted to next gen would not fit on a DVD and so those types of games are not going to appear for XBox 360.