Tools

hello , while I was working on my project ! It’s around 15,000 x 7,500 so it’s huge , While I was building I was looking for some way to mark my land so I went to Y axis view and started marking with textures so I know where the borders of my city is .


Is there any tools to build like huge Mountins that is free ?
Tool to mark borders ?
Tool to place water like with a brush ?
Tool to random generate bumps and small hills ?
Tool to have more brush settings and types !
I’ve heard of Gia but I have so many more important stuff that I need to buy for my game so I’am looking for something else !
Also the brush in unity makes the mountain look like a pyramid and not a mountain