The year is 2438 and life is known to exist on all planets in the solar system. Inhabitants thrive on their own planet whilst war, hunger and intolerance have been eradicated. The solar system is at peace!
The year is 2442 and human engineers develop a vaccine to cure athletes foot. Unfortunately it has a small side effect. Zombification. The infection spreads!
The year is 2445, all but a few zombies have been exterminated and the solar system is almost infection free BUT you have other ideas.
Take revenge on your fallen zombie comrades and infect each planet one-by-one by tapping as fast as you can. Brains can be used to develop upgrades and improve abilities... After all, who wants to tap forever when you can get someone to do it for you?
Go forth and multiply..... claim the solar system for zombie-kind!