If you bought and downloaded PA on Steam, you must follow these steps: 1) Delete the steam.txt file in the PA root directory (if present) 2) Link your Steam account and Uber account to enable you to play: https://uberent.com/user/linksteam 3) Login in with your UberNet account at the main menu
You no longer need to do that. Current version of game have Steamworks integration that works on Linux just fine.
