In this lesson on how to make Among Us in Unity, we will go over building the environment and level design. This is fairly easy to do as most of the level is already created with the background image that we have added to our project. Now if you are creating your own original game then you will need to create your own background image. Once you have your background or map created and added to your scene you will need to create the walls. These are just 3D cubes with the wall tag and layer and you will need to resize and reposition these objects so they are overlapping all the walls of your map.
Next, you will need to create the objects in your scene that the player can not walk through but do not cast shadows. These are also 3D objects with colliders but are set to a layer that does not cast shadows and that our raycast ignores.