hns addon is all about stair, it's kinda hard to explain how hns is played but these are the simple rules:
terro must survive the round by hideing or running from ct and ct must kill terro. terro dont have any weapons, but instead they have grenades (flash and smoke) and ct only have knife. if all the terorist are killed or die in a round, the teams are swiched (ct became terro and terro became ct). i know this is not a very good desription. try to watch these movies to understand the gameplay of hns mod:
if u observ, in hns map it's all about high building and lots of ladders thats why i have long buiding and many ladder.
tha reason that i made square buiding is because if u make skewed walls the players can make "wallbug". watch this if u want so see what a wallbug is