Half-Life 2
After five years of secret development, this PC super-sequel went from rumour to reality at E3 2003, to be followed by a September release. But missing that date was only the start of the bad news: next, the game's code was stolen from Valve's network by a hacker (who revealed its very incomplete state), and a legal battle with the game's publisher threatened further delays even when it was finally finished. It arrived in November 2004.
