The bs01.zip file you have requested: Maps Levels Missions / Portal: Bonus Map - 20.62mb is not available. Perhaps try browsing all files for the game Portal and upload any files you want to share or are missing. This is the only information we could locate:
A map for the Portal game. I tried to be a bit more unique and added balls to the game, and tried to give them a purpose as well. This install comes with a basic and advanced version of the map. The basic version is also availeble for challenges. (po A small bonus map level for portal, containing a basic, advanced and challenges version of the map.