First thing I did was a 3 minute sketch of what the first buildings would look like. I added some elements over it like a water tower, some outdoor stairs and some wooden planks as a way of passing from one building to another. On the second building I added some clothes drying outside, air vents and a way of going on the roof from inside the building. This was my only sketch, because I created the rest as i went along.

  I started the scene with a Polygon Cube, made the building, added the windows, door and rooftop edges. After that i thought that if it's gonna be a game level, it has to have a start/end, so I've started working on a separate scene on the outdoor stairs, from where the character will get access to the rooftops. Next thing I've done was the water tower, the air vents and the wooden planks which let's the character move between two buildings. When working on the second and third buildings i had to hide the first one, because I didn't had much space to go around it, I didn't had enough visibility. I did the same with the other ones. After finishing the scene, I wanted to make a presentation of it in a short video so I've did some research on how to create one. I found out that i had to add some lighting/shadows, and create the camera path. I created the camera path using the Three Point Circular Arc under the Create menu. Modified it's vertexes so the camera would ascend in a circle. On the left you can see three galleries where i showed my original sketch, a breakdown of the scene and each separate element I've used in it. I really enjoyed working on it, even though I still have to work on it, to add textures, background, etc.