These books depend on the administration of violent shocks to the nervous system, and just as the drug addict must progressively increase the size of the doze to obtain the same effect, so, as sensibilities become dulled by the repetition of a particular kind of brutal act, the degree of violence must of necessity increase.
A 20 pager I just started illustrating. The Harvestman is written by Sam Costello and it will be published at Split Lip as a webcomic. Starts at October. Will give you the exact launching date soon as I know it.