Portal 2 timelines

by piotr on June 24, 2012

Or a graphical depiction of the in-game sequence of Portal 2′s character development, plot progression and game mechanics (spoilers ahead).

Click for a way larger view

As a fan of Valve’s Portal 2 video game, I designed this infographic led by my curiosity to get a better grasp on its plot, on how mechanics informed the gameplay, and on the development of its main themes — good vs evil, descent vs ascent, destruction vs construction.


My main source of data was the great Portal Wiki and, though I double checked it by watching walkthrough videos and by replaying the game, you can drop me a line if you spot errors or you disagree with some choices.


I chose game levels as the unit for the charts, i.e. the gameplay between two loading transitions. Because at some point the Portal 2 Wiki counts two levels as one you will notice that my total level number exceed its by one.


Each of the three charts — Characters, Setting and Mechanics — has three axes:

  • the left one displays data types
  • the right one displays total occurrences of a data type over all levels: e.g. Wheatley appears on 31 game levels
  • the bottom one displays level numbers and chapter titles


This chart displays the characters’ alignment toward Chell/the player. Although GLaDOS final stance is ambiguous, I marked her as evil because she turns to her previous self — even if she let Cell/the player go and even if “Caroline is in here too” — and because, as seen on Reddit she will be evil in the multiplayer sequel of the game.


Dark yellow dots marks the first level in which the player encounters the mechanic and has chance to learn it, light yellow dots marks a variation of the same mechanic. Hazards like Toxic water (aka Goo) or Neurotoxin are mechanics, too.

  • total number of mechanics: 28
  • total number of mechanics and their variations: 40
  • maximum number of mechanics in one level: 11, on level 19
  • minimum number of mechanics in one level: 0, on level 34
  • average number of mechanics per level: 6.74 (411/61)
  • mechanics and variations are introduced every: 1.5 levels (61/40) on average
  • most mechanics and variations are introduced at the beginning of the game
  • the three most used mechanics are: Portals (on 58 levels), Grills (on 52 levels) and Grab (on 43 levels)

Post changelog

25.6 added the “Character” explaination

Infographic changelog

25.6 added Neurotoxin on level 30


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