Killology by Gary Owen
In Killology, players are rewarded for torturing victims, scoring points for creativity. But Killology isn't sick. In fact it's marketed by its millionaire creator as a deeply moral experience. Because yes, you can live out your darkest fantasies, but you don't escape their consequences. Out on the streets, not everybody agrees with him. There is an instinctive revulsion against taking a human life. And that revulsion can be conquered.