Overview
Thats what you heard. Playing AT, TWTM and Portal stories: mel maps is very easy and you can do it in 4 steps only. In this guide you will check it out. Also, you will get also the gun model (in AT, its pretty bugged because you shoot portals while shoot gel, its insane, same with twtm, u has the time machine) In portal stories mel, you will have the yellow pgun model. Buts lets go to the good part.
Requirements
To do this you must have:
Portal 2 (obviously)
Aperture Tag (its 10$)
Portal Stories: Mel (its free, just download by searching in the store)
Thinking with the Time Machine (free too)
A bit of file copying and location knowledge
With that, you can move to the next section.
Copying the Files
First, you need to locate the Portal 2 local file. Normally, its found in
D:SteamLibrarysteamappscommonPortal 2
Then, find the maps file, ill place the path there.
D:SteamLibrarysteamappscommonPortal 2portal2maps
This is the path. Now, search for the aperture tag or whatever game you want file. The path for the games:
Portal Stories: Mel: D:SteamLibrarysteamappscommonPortal Stories Melportal_storiesmaps
TWTM D:SteamLibrarysteamappscommonThinking with Time MachineTWTMmaps
(thanks @eat for finding the file location)
Aperture Tag: D:SteamLibrarysteamappscommonAperture Tagaperturetagmaps
When you find the maps folder, double click in it, and select a random map (or a specific map) and left click it. Then, press Copy.
Then, remember the portal 2 maps folder? Go to it, and left click a blank space of the page. Press paste and then just open Portal 2.
Next step needs the console activated. To do it, go to settings > keyboard/mouse > disable developer console > change it to enable.
After this (STILL IN MAIN MENU) press whatever key is under Esc, and a console will open. Enter changelevel <the map you copied name> and TA-DA!
Now you will play a map from one of the community mods of P2 in Portal 2!