Army of the Dead

As chaos comes to the land, you sent your team to stop them, but eventually found out that it is too much for even your team.  You decided that it is time to take action yourself.    The idea here is to take out the army of the dead.  Shoot  them down before they can reach you. You need to hit the weak spot to kill them.  Each undead has different weak spot.  You will have better weapon as you make some progress.  You can interchange between different weapons to fight the undead.  The game will be harder as you see some progress.