I would do a theme similar to Plague Inc. on the Ipad. Start at patient zero and try to infect the world. Evolve your deadly virus, plague or pathogen. Strategy involves morphing it to adapt to be more survivable or deadly.
Play strategy would be similar to the app, spread it by starting specific modes or hitting certain shots or combos. Use wind currents, infect water or livestock.
Anyway, been awhile since I played the game, but I always thought this would be a killer theme. Probably not very timely with Ebola, but a great theme no doubt.
You could also make this a pin where you choose sides. Don't like killing people? How bout trying to create a cure. Be a hero!