I literally got shivers down my spine when I saw this game was available on GOG.com. It's the one I've been looking for the most (along with Death Rally).
This game is a very unique town sim, where you have to manage everything from buying land right down to the bathroom of the first shed you've built. You simply don't stop clicking. When you have a deadline, seconds count and you can't hesitate. And that's playing all by yourself, no AI involved.
Like another reviewer said, adding a single AI opponent in the easiest scenario turns Constructor into a different game. To be able to beat the scenario with AI, the management of spawn rate, income and resources have to be absolutely automatic, because you need time to think up a strategy to beat the challenges that come with adding AI enemies.
It's an incredible game, a must-have for anyone who likes town sims. Truly unique.