Uplink is a geek's game in which you incarnate a hacker that performs various internet-related hacking jobs.  

U-Boat is a WWII submarine simulator. You are in control of a German U-Boat, setting off on patrol in the early stages of the war, from a port in Germany, into the North Atlantic, and eventually to the Mediterranean. You receive messages...

Is it a game? Is it adult-themed? Is it nonsensical? It's certainly a piece of interesting shareware history. It's Underwear Girl, a dressup game with no endgame other than your own desires. Speaking of which, the secret code is...

Underwear Girl 2, sequel to the original but now with more animation, dancing, music, and more. This time, the "secret" isn't a code you input, but was a special version of the file you received from the author, who provided the...