Nobody knows who started it. A dozen terrorist organizations and a couple of countries claimed the first strike, but then everyone let loose. Bioweapons and nanites spent a week wiping out the majority of the world's humans, and reanimating most of them into flesh-hungry zombies. Another nanoweapon has rendered gunpowder inert, so it's difficult to do much about it. You, the survivors, have carved out a stronghold in the midst of the city and plan to take it back.
Part RPG and part turn-based strategy game, Stronghold uses a very simple, diceless system for most tasks. You'll need to grow or find enough food to survive, and gradually recruit additional survivors and expand your stronghold until you control the entire city. Along the way, you'll have to deal with zed attacks, nanoswarms, and the occasional nutjob.
Good luck, and stay strong.