I just tried the sandbox demo on Steam last night, then immediately upgraded to the full version. It's a wonderful, fun tool for the price point.
The full version has a story mode, but they've also included the full sandbox mode where everything, every tool is unlocked and you have no cash limit. The computer also has an app that will give you a prompt if you're stuck! The studio is fully upgraded and you can just mess around to your hearts fullest. I fully recommend getting the full version if you had fun in the demo, if you haven't already.
Secondly, DO NOT LISTEN to anyone who says you lack imagination. They sound like a real brick, my dude. You do not lack imagination, you're full of it. Creativity is the providence of everyone, and this game is a wonderful way to explore building a positive relationship with your creativity and the creative process. You deserve to participate in that.