In the past Konami denied outright and most recently back in August, Konami said "probably not possible" to queries if MGS will come to xbox 360. During the TGS, Konami's spoke person, said that "The worldwide demand for an Xbox 360 version (of MGS4) is quite high, and it is something we are currently looking in to."
Konami is a third party game developer. It was easier to comprehend why there were so many exclusive titles for PS2 vs xbox. Have a look at the sales figure for the two. Now that XBOX 360 has an installed base of more than double than PS3 and if the trend continues, the gap will be bigger in months to come.
Heh! why stay exclusive to a console that sold only <>5mil when you can also port the game to another console that sold more than 10mil? Imagine Konami makes $20 out of each game sold and game is sold to 30% of xbox 360 owners. that would be like additional $60,000,000 for Konami. I still cant comprehend why not all non Sony own developers not in the xbox 360 wagon already!
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Morningstar recently put forth that multi-platform releases are becoming more common in the gaming industry in order to appeal internationally. To that end, the Japanese investor publication spoke to Konami PR rep Yoshitaka Arai at Tokyo Game Show about the possibility of a multi-platform release for Metal Gear Solid 4, currently a PS3 exclusive title.
"The worldwide demand for an Xbox 360 version (of MGS4) is quite high, and it is something we are currently looking in to," said Arai, according to a Kotaku translation.
Metal Gear creator Hideo Kojima commented in late August that Metal Gear Solid 4 on Xbox 360 is "probably not possible."