I don’t know if Timezone was ever released for the PC. I think so, but maybe not. It was one of the first games we ever did and was released prior to the IBM PC introduction.
Many of our old games can be found on websites around the web. There are emulators that will play them. That said, I’m not sure where to look. So — good luck!
PS Check out http://www.kensgame.com — I’m working on a game now with Roberta. It’s a long way from release but .. register on that site and I’ll keep you up to date as we make progress.