The ground looks 3D but when you click to create a platform over it, it's created in front or over the layer making it look like a 2D background, and it does not look very well.
And moreover the platforms are not created where you want them,i.e they are a few pixels below the cursor.
I hope you fix that.
Also like Other person pointed out that it is possible to create multiple platforms, I could keep randomly creating new platforms all over and watch them fall for about a minute.
I suggest you create a reload time where, when you create say about 5 platforms you require a cool down until you can create another set of platforms.
Also the background is well designed but the platforms also need some depth to make it look better for the whole game to be complete !
Just some plain thin line would not suffice for the concept to come together.
Adding some music and sfx would also make this game viable to be released on Mobile Platforms.
Well done on you game concept and Hope you fix the issues.
Good Luck further !