Dushanth Mahendran



Level Design Document

Assignment 3

GBGD203 Game Level Design

May 2015

Dushanth Mahendran


Table of Contents


This level is a single player level made for Valve’s Portal 2. Set in a post-apocalyptic world, the player has to survive numerous tests and escape the testing facility of Aperture Science before they are killed by the experiment-fanatic robot left in charge of the facility.


This level is aimed to take place at the start of a new optional campaign. This level introduces a new mechanic not used in the main story campaign: Time Travel. It is recommended that the player has played at least a quarter of the main story campaign before attempting this optional campaign.


The goal of this level is to introduce the time travelling mechanic to the player, before the player attempts the later levels involving more advanced uses of time travel. As such, this level has to be simple enough as to not confuse the player as they learn time travel, while being challenging enough to invoke more interest in using time travel in later levels.

Player Objective

The player has to navigate through several test chambers using the new time travelling mechanic and solve puzzles in order to solve a test chamber before proceeding to the next test chamber.


Player Skills Required

This level is available as the first level of a new campaign focusing on time travel, and so not much is required for the player to know except for the basics of Portal 2 gameplay.

The player is required to:

  1. Know how to move and jump
  2. Know how to interact with objects and pick them up or active them
  3. Know the interaction between a cube and a button
  4. Know how to place both the blue and orange portal
  5. Understand the physics and interactions of portals
  6. Know what surfaces portals can be placed on
  7. Know the interaction between the fizzler, cubes and portals
  8. Know that laser fields are deadly to the player (Optional)
  9. Know the effects of blue gel (Optional)


In this level, there are two different aesthetics that make up the entire level, based on the time the player is currently in. This can be seen on the next page.

The Clean, Sterile Past

The past is very clean and free of clutter. Nothing is broken and every device found in the test chamber is working. This past is set shortly after the events of the apocalypse, just after the human researchers in charge of the test chambers were killed by the robot currently in charge of the facility. Test chambers are devoid of any clutter or unnecessary items to not distract the test subjects (the player) and not affect the test results. Walls, floors and ceilings are either black (portals cannot be placed on these) or white (portals can be placed on these).

The Dilapidated, Overgrown Present

The present is unkept and overgrown with vegetation. Many devices, and wall panels are broken and non-functional. The present is set many decades after the events of the apocalypse. During these many decades, the robot in charge of the facility has been shut down by a test subject who tried to escape the facility. Due to this, there is a lack of supervision on the facility, letting it fall into ruin. During this present, the robot has finally been reactivated and is now very ill-natured towards the test subject that deactivated it in the first place.

Running the Level

While the level was placed on the Steam Workshop for easy installation for playtesters, it has since been taken off the Steam Workshop upon the end of the assignment. Hence, the level has to be manually installed and started to be run.

  1. Navigate to the install directory of Portal 2, and then head into the folders “portal2” and then “maps”. Place the “2015_3_DushanthM_A3.bsp” file here.

  1. Launch Portal 2 and go into “Options” and then “Keyboard/Mouse” and change the “Allow Developer Console” to “Enabled”.

  1. Go back to the main menu, and press the tilde key (` or ~) near the ESC key on your keyboard to bring up the Developer Console.

  1. Type “map 2015_3_DushanthM_A3” into the Developer Console and press Enter on your keyboard.

  1. The level should start loading.

Quick Walkthrough

Test Chamber 1

  1. Walk up the stairs into the first test chamber.

  1. Go through the time machine to the Past.

  1. Put a Blue Portal on the floor where the Blue Repulsion Gel falls onto.

  1. Go through the time machine back to the Present.

  1. Press the switch to activate the white panel.

  1. Put an Orange Portal on the white panel.

  1. Wait for some Blue Repulsion Gel to fall out of the Orange Portal and onto the square panel on the floor.

  1. Jump onto the Gel-covered panel and go through the door.


  1. Step on the button.

  1. Put a Blue Portal on the marked white panel above the ceiling.

  1. Put an Orange Portal on a white wall.

  1. Go through the Orange Portal and navigate across a steel beam into the next room behind the shattered glass.

  1. Walk past the computers and through the next door.

Test Chamber 2

  1. Go through the time machine to the Past.

  1. Press the switch to open the door.

  1. Put a Blue Portal on the wall in the room after the newly opened door.

  1. Put an Orange Portal on the white wall next to you.

  1. Go through the Orange Portal.
  2. Pick up the Cube.

  1. Go through the time machine back to the Present with the Cube.

  1. Press the switch to open the door.

  1. Put a Blue Portal on the wall in the room after the newly opened door.

  1. Put an Orange Portal on the white wall next to you.

  1. Go through the Orange Portal with the Cube.

  1. Place the Cube on the Cube Only Button.

  1. Place an Orange Portal on the white panel on the ceiling that has just flipped.

  1. Go through the Blue Portal.

  1. Place an Orange Portal on the floor.

  1. Go through the Orange Portal and pick the Cube up.

  1. Go back through the Blue Portal again and place the Cube on the button.

  1. Walk through the door and finish the level.

Level Layout Analysis

This level is treated as an introductory level for a campaign involving a new mechanic, which is time travel. Due to this, the puzzles involved in this level has to be able to teach the player about the new mechanic effectively without the use of tutorial prompts.

Upon coming up with the initial design of the test chambers, I followed several guidelines in order to make the levels more effective in teaching the player about the new mechanic. They are:

  1. To make the puzzles simple and involve only one or two gameplay mechanics in addition to the time travel mechanic, to ensure that the player is not distracted or confused by the other mechanics.
  2. To keep player direction simple by making the levels turn one direction only at most times so as to help players associate the new time travel mechanic with this one direction.
  3. Make test chambers involving the time travel mechanic as similar to their time counterparts as possible, so as to ensure that the player understands that time travel is the key mechanic.

With Guideline (2), I drew up an image that will serve as the guide for the shapes of the test chambers:

According to this image, the player direction, or the directional flow that the player will constantly follow, is constantly turning right. This helps the player associate the right hand side direction to the time travel mechanic, making the time travel mechanic more natural as they continue to turn right using the time machine. This is seen in both Test Chamber 1 and Test Chamber 2:

Test Chamber 1

Test Chamber 2

Test Chamber 1

This is the first chamber to involve the time travel mechanic, and so has to be the simplest one in order to teach the time travel mechanic effectively. Also, the player is allowed to time travel as many times as they want without restrictions in order to understand what it means to time travel.

Just before the player enters Test Chamber 1, they will see this poster about time travel to hint that the player may be experimenting with time travel in this level.


Upon entering the test chamber, the player will immediately see a new device they have never seen before in the game: the Time Machine.

Since there is no access to anything but the time machine at this point, the player goes into it and comes out in a room that isn’t run down but instead is very clean and sterile. When the player decides to reenter the time machine they will appear back in the Present, where everything has deteriorated and overgrown. The player will then understand what is going on: They are travelling to the same room, but at different times.

Making the player put Portals in both times will help reinforce the fact that portals stay persistent whenever the player time travels and that anything going through the portals, despite from a different time, will appear on the other side unchanged. This keeps the physics of Portals in the game constant with what has been established by the main game, which is that items and beings going through portals remain constant.

The only mechanics used in Test Chamber 1, besides the Portal and Time Travel mechanic, is the switch mechanic and the Blue Repulsion Gel mechanic, both of which are simple to understand and so shouldn’t distract the player from the main mechanic being taught here.


In Portal 2, breaks are occasionally placed in between test chambers. During these breaks, or intermissions, the player isn’t required to solve a puzzle most times and serves mostly as a point at which narration such as cutscenes and dialogue are given to the player. Sometimes, intermissions are used as a way to get in between test chambers. The Intermission for this level serves this latter purpose: To get the player to the next test chamber while giving them a short detour through the broken down facility of the Present time. The time travel mechanic isn’t used here to give the player a break and time to ponder over the new mechanic, before presenting their next test chamber involving the time travel mechanic.

Test Chamber 2

This second test chamber serves as practice using the time travel mechanic. It makes the player travel through the time machine multiple times in order to solve the test chamber. Also, this time, a restriction is put in place. A glass panel separates the two time machine sections, stopping the player from continuously time travelling easily.

Like the first test chamber, this one follows the right-only direction guideline to help the player learn the new mechanic easier using association. The additional mechanics this time involves switch and cube-and-button mechanics.