How can i make a 2D house with stairs

Like a game name Project zomboid player can walk on 2D stair .pls help .
You can see picture with this link . Thanks.

https://www.google.com/search?q=project+zomboid+stair&rlz=1C1GKLB_enVN668VN669&espv=2&biw=1024&bih=599&source=lnms&tbm=isch&sa=X&ved=0ahUKEwiu-uOend3LAhVCIKYKHZiJCy0Q_AUIBygB

That game is in 2.5D so the objects are positioned within a 3D space. That means the stairs are just regular 3d stairs which you can use the BSP brush for. What kind of game are you making, then I could give you a better answer?

I want to make a top down open world game with some rpg element and house building. Many thanks

Using 3d models is absolutely fine from a top down perspective, you just have to make sure that the camera is set to Orthographic instead of Perspective (unless you want a perspective view!)

I am very bad in using blender that’s why I want to make 2d games .maybe I have to learn 3d . Thank for advice