In 1990 or so, my friend and fellow Future Shock Software guy Steve bought a floppy disk in a computer software store for something like $10. On it were 3 games: some space game, a pretty decent Ultima 2 clone called Ranadinn, and a little game called "Hack". 

Hack was an offshoot of Rogue, which you may know from the term "Roguelike" which is applied to basically any game released nowadays, accurate or not.

Steve and I initially scoffed at Hack and its primitive ASCII graphics. But after a few hours of gameplay, we were hooked.