Is there a printed manual? A lot of publishers, even the big names, are skimping out on the game manuals. Not even included .pdf files anymore. Just a link saying 'for more information on gameplay, go to this specific page on the game's website'. And those that do include anything printed are more like folded reference cards, for all the lack of content.
On the other hand, I suppose most of the fun in Postal is discovering the rewards and consequences for shooting (or not shooting) things. And faces.