The rusta2.zip file you have requested: Maps Levels Missions / Single Player / Rusta 2 - 3.14mb 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:
Rusta (1-2 min challenge map with crazy textures, version 2) It consists of 64 * 64 u blocks only really and looks insane. Texture purposes are consistent (one is portal'able, one is not, one kills you). I really don't know about the steps challe This is a 1-2 min challenge map with crazy textures.