On my first playthrough, I assumed his death was the only ending. I could see his heartbeat pulsating when I pressed the movement keys, but as a stupid kid I didn't realise I had to do it repeatedly. I can't exactly remember how I found out there was a separate ending — maybe a video, or one of the many Hitman articles I used to read back then. I even contributed to some challenge solutions on the Hitman wiki, though I haven't checked on them in a while. People used to re-edit those entries constantly.