"On October 24, 2005, 3D Realms (formerly Apogee) released a maintenance patch to fix a bug in the game which set the player's computer's clock backwards 100 years after playing on Windows XP." lol.
Secret Agent, anyone? I still love that game. In fact, all the old Apogee games had a sense of mystery and discovery that's sorely missing in modern titles. (Or is it nostalgia?) I remember playing through so many shareware titles and salivating at the new goodies that the nag screen promised from the remaining two episodes!
By the way, Apogee has released a lot of their old titles for free. You can find them at 3drealms.com, in the Downloads section.