http://www.youtube.com/playlist?list=PL1D45D50A82ED096F Basically, as same as Hard. However, the enemies contain more HP The Gate on Roof Top - Uses Handgun to break the gate with 6 bullets The Gate of Apartment - Shoot the door with all guns !!! However, you should run around the area, to avoid the attack and let the enemies change their target. Don't stay a position too long, every 5~10 shoots of Handgun (or Nail Gun), move yourself ... https://www.youtube.com/watch?v=hhulILz7iWA

Challenge - Find the secret room 0:00:03 - Clearing the path. 0:00:07 - Waiting the zombie alive and explode to kill the 1st attacker. 0:00:10 - Let the zombies jump over the cracked floor. 0:00:11 - Explode the zombie to kill the 2nd attacker. 0:00:14 - Let the zombies jump over the cracked floor except the last zombie. 0:00:17 - Clearing the path. 0:00:22 - Explode a zombie to destroy the destructible floor. 0:00:25 - Explode the zombie to kill the attacker. 0:00:31 - Let the zombies jump over the gap on the underground floor. (Some zombies may alive) 0:00:48 - Clearing the path. 0:00:51 - Explode a zombie to destroy the destructible floor. 0:00:52 - Contamination the shotgun attacker. 0:00:54 - Explode a zombie to destroy the destructible floor. 0:00:57 - Explode the zombie to kill stick attacker. 0:00:58 - Explode the zombie to kill handgun attacker. 0:00:59 - Explode the zombies until find the secret room. Remark: This play through uses 10 zombies to find secret room. ... https://www.youtube.com/watch?v=oi25aG0zi8Q