While I'd never stoop to the old "games cause violence" argument, there's little doubt that games teach us to treat death as a numbers game. Each individual demise isn't important: what matters is the body count, the chain reaction, the comforting tick of small numbers getting bigger.
Pandemic, a morbidly fascinating disease simulator from Dark Realm Studios, is a game that, played successfully, trades in enormous numbers. Get things right and billions of people will die, yet it's always that first death that feels the most exciting and special. It means you're on the right track. The counter will rise.
Pandemic started life as a Flash game on the Newgrounds website that went appropriately viral, but it's been heavily redesigned for its first paid outing as a 69p app. Not all the changes have been for the better, but the ghoulish core of the game has survived intact. If you ever wanted to exterminate mankind, here's your chance.