Really fun and easy, just takes a few tries and before you know it you're on the next level. It's addicting, Lightly challenging, and it follows the laws of physics as if it were real. I say it's an awesome game, Really fun when you take up the entire screen because you destroy everything you touch.
Oh, and to BC (Best Commenter) Nauto, a good way to use Tier IV is to get the world infected, get the numbers of healthy to near 0, and strike em' dead with heart faliure.
An exellent game by all standards, extremely realistic in realistic mode, challenging, groundbreaking, and so exiting that when you infect most of the world you get out of your chair and shout "YES!!" I proudly present them With * * * * * (5 stars)