First concept of ruined city.
Original prison concept
The game starts off with you playing as Clip who is basically the average joe/rookie who hasn't had much field experience. Clip along with Shell have to rescue Barrel (Heavy character) from being imprisoned by the security forces of the city. My original idea of the prison was that it was outside the city limits in an old nuclear power plant that would be connected to this fortress city by the bridged motorway section.
As the idea of the motorway network was taken aboard by the group, I got to work on designing the intersection so that I would be able to fragment areas of the city into different levels as the programmers wanted 3 playable levels.
In the above design I wanted to work out a motorway intersection that would ultimately play as ruined skyways above the slums from which patrols could operate on. The square in the middle represents the pyramid structure that would be the heart of the transport city. Using this drawing, I could roughly map out level 1 which I was assigned to design and model.
With level 1 roughly mapped out, I knew what kind of area space I had to work with. After showing the team the proposed idea for level 1 they suggested it would add more of an element of game level design if I restricted certain areas and made it so that there is only a limited number of routes to progress. I did this by creating 3 districts.
The 1st district would be a trainyard from where Clip and Shell would begin the game. The 2nd district would be the slums where the majority of the people would live and the 3rd district being an old coach station converted into a military outpost/prison where Clip and Shell would need to rescue Barrel from.
I first turned my attention to district 1, the trainyard. I wanted district 1 to be an open environment yet at the same time I wanted to make the player feel like they are at the bottom of a ladder and have to climb up to discover the rest of the city. I felt that this would work well in terms of progressive gameplay and it also fitted in very well with the general storyline of the game. The characters would emerge from the abandoned underground tunnels to find themselves in an enormous trainyard/freight yard. They would've avoided all the patrols along the city walls and moved in undetected however the price to pay for that move would be to start from the lower levels of the trainyard and work their way upwards to the street level.
To create this layered almost urban rainforest look I designed the trainyard with layout paper.
Motorway Level (top level)
The motorway level is also layered with 3 different heights of motorway overlapping each other.
The middle layer would be the road level which the rest of the districts would rest on.
The bottom layer being the actual trainyard itself. This layer consists of support beams from the above layers, tunnel entrances and train tracks.
The above image is all layers compiled together on photoshop. The red line represents the route that the player must take to progress to district 2 however the entire trainyard is free to explore and extra health and ammo could be found if it is explored properly.