I've been making the odd 3D game demo's/tests for a while and just started my hand with Construct 2 for some 2D games.
A suggestion I have for creating a top down landscape is to use this free 3D terrain generator... L3DT
It's very easy to create and shape a 3D terrain, and then just use the texture file as the background for your Construct 2 project. You can tile the terrain if you so wish too.
Hope this helps someone. <img src="smileys/smiley1.gif" border="0" align="middle">