I was playing Portal 2 co-op for the first time. We were on PC in split-screen mode. When the game started, we were dumped into a level selection chamber, and a voice announced that all levels were now unlocked.
Why did this happen? In addition to not having unlocks, there was apparently an intro cut-scene and a tutorial level we missed?
This is actually a feature. Here's Portal 2 developer PersonGuy's explanation:
Because the game is running 'offline', it doesn't have access to the progress data in Steam. To make this work we'll need to rewrite quite a bit splitscreen session code that assumes multiple log ins.
So instead of making you start at the very beginning every session, Valve just unlocks all the levels for local co-op.
As for the intro cut-scene and level, those may be accessed by pausing the game in the level select chamber and selecting the menu item for "Calibration course."
