Your able to completely customize your hero giving a lot of diversity to the game and high re-playability, in other words if your willing to always change it up to learn new things the game can never get old, it has endless possibilities.
The main owner CHF clans are Clan HPMM and Clan CHF along with many others.
The Official web site to explain more can be found by Google searching the name, first hit probably.
Bottom line, the game is one of the best, if you haven't tried it yet your missing out until you do. (AI is also insane for it)
Person B: No.. why?
Person A: Its by far one of the most legit custom games made it even has about 4x the microing DotA requires, its amazing!
Person B: Hmm so...should we play now?
Person A: I'm already playing..