Portal 2

Portal 2
steam://rungameid/620

Game Program Files
C:\Program Files (x86)\Steam\SteamApps\common\Portal 2

Game Save Data
C:\Program Files (x86)\Steam\SteamApps\common\Portal 2\portal2\save

Multi Player Co-Op
Blue and Orange robots

Reset Co-Op Progress
Reset Multi Player Co-Op Progress. This is especially useful for people looking to experience the transitions and extra few GLaDOS lines.


 * 1) Launch Portal 2.
 * 2) Select "Play Cooperative Game"
 * 3) Select "Standard Co-Op"
 * 4) Invite your friend to join and start a session
 * 5) From here, open the Console (default ~)
 * 6) CONSOLE COMMAND:
 * 7) CONSOLE COMMAND:
 * 8) CONSOLE COMMAND:
 * 9) Exit the multi player game, start a new multi player game and your progress should be reset.

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To unlock course 1, use

There is also  if you want to get Professor Portal. (after finishing coop, play with a friend who hasn't played yet)

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References:
 * How do you reset saved multiplayer progress in Portal 2? - Arqade - http://gaming.stackexchange.com/questions/20459/how-do-you-reset-saved-multiplayer-progress-in-portal-2
 * How do you reset saved multiplayer progress in Portal 2? - portal-2 - TechQues.com - http://www.techques.com/question/10-20459/How-do-you-reset-saved-multiplayer-progress-in-Portal-2
 * Restarting coop from scratch - PC : Portal - https://www.reddit.com/r/Portal/comments/2rx5hu/restarting_coop_from_scratch_pc/