Direct quote
“ポリスノーツはもっとも難産だった作品である。企画立案から最初の商品化（9821版発売）に至るまで4年もの歳月を有した。” JA Original quote in Japanese; the summary below carries the meaning.
What it documents
In a text written for Konami's website, Kojima described Policenauts as his most difficult birth: it took four years from planning to the first commercialization and six years in total including later conversions. During that time his department changed three times, and the organization, his position and his work environment changed repeatedly, while the world moved — the Berlin Wall disappeared and the Cold War structure collapsed — and they were also struck by a large, unexpected earthquake.
Source
Konami, official website: message from Hideo Kojima on the Policenauts page (PSone Books) (page 1 of 2). View source ↗
“その間、所属部署も3度変わり、組織も立場も環境も幾度となく変わった。勿論、時代（ベルリンの壁が消滅し冷戦構造が崩壊する等）も大きく動いた。予想だにしなかった大震災にも見舞われた。”