Low poly advanced chunk procedural generation

First of all this 2 images is maded in blender.
The (image Nr. 1) is the subdivided plane with flat faces and the second one is the same plane but with Decimate modifier to 0.5
Talking about the low poly generation i have done this ( image Nr.1 ) in unity using C# of course. How i can generate the second image in unity ? Do you know maybe some similar situations or some generations of this type of triangulated low poly ?

I assume you don’t want an actual Decimate function but you liked what the pattern it made looked like? You will need to learn how to generate meshes. This is covered more fully than I can say helpfully at this link here

After you learn the means to add/manipulate vertices, you can start just by randomly manipulating the vertices of an already low poly plane or even just generate the points and their order for that more rugged terrain look. Once you have figured out how to generate a chunk the way you like, you can then make a way to stitch them, perhaps by making the edge vertices meet at the same position. This might be tricky if you use a decimation algorithm, as your edge vertex count might not match the chunks around it. However you generate your chunks, you will want to make sure that they can stitch together so you don’t have holes.

If you want to get the effect of the decimation you may want to look at this repository for a library with a decimation algorithm that may be handy. Sorry there isn’t a one or two click solution to your needs but I think this will get you going at least.

Doing decimation at runtime seems like overkill. It might be better to flatten #2 in Blender and then displace random points in Unity. Or just make several variations of the mesh in Blender and import them into Unity. Would anybody notice? I suspect the human brain could only distinguish between 10 variations.