@zomtron To clear things up: energy is basically everything, not just fire. There are two main types of energy that I know about: kinetic and potential. You are correct about the fact that there is energy in fire, the molecules in the fire move so fast that the friction between them create heat...then POOF! fire! Hope this helped explain things. :)
The only thing I dislike about this is how fast the people with guns kill the zombies, the second one has amazing improvements on that and many other things. I strongly recommend it!
Thanks. I thought no one will even bother reading the wall of text... :D