Simple answer: Head shots. You have to shoot him in the head for the first part of the battle, except when he's about to do that ground pound thing (that's a no-damage mode for him). You'll see his head flash white with each hit that damages him. The second part of the battle starts when he "goes nuclear" as I put it, or when he shoots fireballs out in a circle. After that, any hit hurts him, including body shots. The ground pound no-damage mode still applies though. As to dealing with fireballs, you can try to dodge them, but you will probably still be hit. The best way to handle them is to shoot them; one shot will stop a fireball. The best weapon for fighting Rufus (easy or hard) is the assault rifle. While the rocket launcher looks like a good choice, the sustained fire you'll need to stop fireballs and hit Rufus will overheat it very quickly. The assault rifle, however, has a fast enough rate of fire to stop groups of fireballs and still hit Rufus, while also having a quick enough reload time to not get you killed while reloading. Additionally, it has a good enough damage rating to keep the fight from lasting Too long, and it is more accurate than the other guns (except the rocket launcher). I find that the best combination of equipment for fighting Rufus is the assault rifle, jet pack(can help dodge fireballs), and "super shell." Switching to the rocket launcher after Rufus goes nuclear is an option, depending on your preferred style of gameplay, but overheats are still an issue. _____ Still can't get into the last three levels though, even after some very long runs and high kill counts.
