Still, quadropolis requires the downloads to be ZIPped ...
... there is no point in jumbling multiple packer-formats around on this site.
ZIP is just universally available and really good enough,
even if someone might personally prefer any other packer.
And BTW: I've had a couple of cases where I couldn't unrar with the linux version ... not to say I didn't get at the files - but we're trying to make life nice and easy for potential users of the site ;-)