Three years ago, I have beaten this game. I thought I don't need to play this game again since I completed Saga of the Dead. But, someone keep on pressing and forcing me to play this game again though...*Sigh*.  So, this time...I played on Hard Difficulty. Some differences that I notice while playing this mode are:

1) John Creasman don't talk to himself about escaping the city
     after the intro cutscene.
2) More debris and obstacles on the highway.
3) More running civilians to avoid.
4) John Creasman's bullet resistance has been reduced (Which
    means you'd die easily compared to normal difficulty).
5) Weak windshield. The windshield will usually last near at the
    end of checkpoint 5. It can last a bit longer if you know how
    drive and dodge bullets.
6) More soldiers on the road (I think...).
7) More mutants. They usually spawn at narrow spaces which are
    annoyingly hard to avoid. Sometimes, two or more mutants
    would also spawn really close to each other. You need to know
    how to fool each and every of them. Gotta save those 9 slugs
    for later emergency only.
8) Biggest threat...More Hellfires (I think...). I took down 9
    choppers in this run. It could have been more if you drive too
    slow. In the last 2 checkpoints before the tunnel drive, the radio
    wouldn't tell when the choppers are chasing you or firing
    missiles at you, always be alert on that.
10) I don't know if this is a bug but that carpet bomber keep on
      dropping bombs even at the last checkpoint. They should have
      been fall back at that checkpoint...I mean what the hell is
      going on, Evil-Dogs?

I still think my first run three years ago is still better than this run. I can't play this game like I used to back then because I lost touch and want to move on to other games. I kept on stopping to avoid that annoying Squad Bomber, screw them!

I hope you enjoy the gameplay, not the best gameplay. Someone can do a better run than this though....