I'm sorry for getting your hopes up in vain. Good luck in finding a copy of the game. Have you tried second-hand shops?
A movie would be really good, because the game has interesting characters, storyline and setting. The question is which would be better, a direct adaption of the game, or a new story using the same characters and background (similar to Resident Evil but keeping the game characters). Maybe a prequel showing how Hana and Rain met? Or a sequel set after both games?