Fin #1

In one sentence:
I wish to build a b&w (and yellow) mission game, controlled by a sandbox filled with small particles.

1. How does the sandbox control the game technically?
2. What is the mission apart from the simple command “PLEASE PUT IT BACK”?
3. Where do I start? I need to plan the game in such a way that I can manage to build it eventually (I’m a slow code writer).

It will be beautiful.