Use WASD to walk around.
Collide with zombies to fight.
in battles, the winner gets the undead troops of the loser.
When close by castles hover over them with your mouse for action options.
If a castle is yours you can deposit and withdraw undead.
enemy castles you can siege.
you siege castles to get more brain power to cure the zombie infection.
if the living population drops to 0 in all castles you lose the game.
get the cure to 100% to win.