It's now widely known that Sony's Gravity Daze (or Gravity Rush as it's known outside of Japan) was originally planned as a PlayStation 3 title but was changed to PlayStation Vita at some point. So when was the big platform switch made?
Famitsu.com posted a report from a "PlayStation Vita Game Conference" event that Sony Computer Entertainment Japan held at its office on the 28th. A session on Gravity Daze was lead by Makoto Isomine of Sony Computer Entertainment Japan Studio Internal Development Division.
According to Isomine, the switch to PlayStation Vita came around 2009. The system was not known as Vita back then, of course. Internally, the team thought of the platform as just "New Portable Game Machine." They conducted basic research into the platform while also working on Gravity Daze's design.
Isomine credits Sony Computer Entertainment Worldwide Studios president Shuhei Yoshida with suggesting the switch from PS3 to Vita. (A slide shown in Famitsu.com's coverage shows Yoshida saying "How about PS Vita for Gravity Daze?").
Gravity Daze's development began in summer 2008 with the concept of mixing the essence of French comics, Japanese animation character traits, and American comic heroism, along with the basic gameplay idea of free gravity. A couple of weeks back, Sony shared a concept movie that was shown internally in 2008 (see the clip here). This was developed in Maya to show what would be possible when making the game on PlayStation 3.
The development staff was very small when the Vita version started development, with just two programmers. Eventually, the team would blow up with over 15 programmers in the end.
Despite the small size, the staff had to work not just on the Gravity Daze project as they'd conceived it, but on showing off PlayStation Vita's special capabilities. This was a requirement that Sony placed on all titles whose development was progressing simultaneous with the Vita hardware's development.
Because the Vita hardware wasn't ready yet, the first step in making the switch from PS3 to Vita was to move development to Windows PC. Lead Programmer Yu Yokokawa explained that while development in a Windows environment is common for third parties, it's rare for first party teams at Sony. There are merits to development on a PC environment, acknowledged Yokokawa, including the ability to immediately test out things without giving development systems to the entire staff.