I created mega menu like this many times with custom HTML & CSS.
But I can't find a way to create it in DNN custom skin. In my skin I use:

<dnn:MENU MenuStyle="Simple" runat="server"></dnn:MENU>

For menu.
Can someone give me directions what to use to make nav menu like above in custom dnn skin? 
There must be some example somewhere.

Please people I need help. There is lack of documentation about this topic and I am trying to make this for weeks and really trying hard to force dnn in my project.

When you say '... that menu' you certainly think on dnn:MENU. I suppose that I should use ddr:MENU but if I enter ddr instead dnn I get error unknown tag. And on the beggining of my skin .ascx file I have '<%@ Register TagPrefix="dnn" TagName="MENU" src="~/DesktopModules/DDRMenu/Menu.ascx" %>'.
Do you know why this can happen?

I have just tried those templates (I am using dnn:MENU) that you posted and they works. Mega2DNN is the closest to what I am tring to make. But it use XSLT and I wan't to learn RAZOR. Problem is when I try to use template with RAZOR my menu disapear.
Do I need to set up something so I can use RAZOR syntax for templates?
I am using dnn 7.2.1.

Any support here?