The Game Idea is very Good but it is incredibly Easy.

Maybe make it more difficult, Because at the moment there isn't any advantage to decreasing the scale unless the Pass way is small. Also The Level completion point is weird a bit, You should probably make it so that unless you Don't hit the level completion collider directly the level is failed. And that brings me to my other point, there is no level fail, And every level is Easy. 

A good idea and a good game nonetheless.