1995: Announced - Tom Hall produced number of designs
1996: Tom Hall left - Paul Schuytema brought in - very first versions of portal technology used
1997&1998: Portal tecnology shown at E3
1998: Team disbanded
1998-11: Corrinne Yu brought in as engine programmer
1999: Development stopped/put on hold - Corinne Yu left - was not cancelled contrary to popular belief
2001: Development of a new version started, 3D Realms licensed id Tech 4 (Doom 3 engine) - Human Head Studios were commissioned to continue development based on earlier work.
2002: Rumors of the new project leaked to public
2005: Cryptic clue given about Prey's release: "Keep your eyes open for the unveiling of our next game very soon. ;)"
2005-04-26: Prey officially announced
2006-06-22: PC demo released
2006-06-28: Gone gold
2006-06-30: Xbox demo released
-: Released



source: en.wikipedia.org/wiki/Prey_%28video_game%29#Development_history