Scott Miller didn't create the try-before-you-buy concept of shareware, but he was the first one to make it profitable. In 1987, Miller realized that selling an entire game online would not make money, so he put his marketing education into action and split his 75-level Kroz game into three episodes, releasing the first episode, Kingdom of Kroz, as shareware. It served as a self-perpetuating advertisement for the remaining two episodes. He was soon bringing in more income from his game sales than from his day job - as much as $500 a day and $2000 per week.
This game was included in issue 20 (June, 1988) of Softdisk Publishing's Big Blue Disk magazine.
You could buy the source code of this game for $190. It's programmed in Turbo Pascal 3.0.
The name "Kroz" didn't come out of a hat - it was Zork spelled backwards, probably as an ode to Infocom's game
This was one of Apogee's first games - it's since been discontinued, but at the time it was so popular that it spawned six sequels.