It's a RTS colony builder game like Age Of Empires but with a Steampunk theme and you have to defend against zombies, just like in World War Z.
You start with the Command Centre and have to build everything from there advancing up the tech tree as you go.
You also have to balance homes which give you workers but consume food, resources which produce food and wood and stone etc but need workers and energy and energy buildings that need food and workers.
Then you have to build walls, soldiers and so on ...
Then every so often, the zombies swarm. You have to survive a certain number of days, on the easiest settings it's 150 days, and even that's not easy.
Oh and you can save the game, but then HAVE TO quit to the menu. You cannot reload a save from a previous point, ie if you save and exit to menu, you rejoin at that point. If the zombies take out your command centre ... it's game over, man, game over!