@flameinpain, the red slimes are immune to magical damage... read the entire description because there is more useful information than just their elemental weaknesses.
It really isn't all that hard, I recommend that you use the hunting rifle as soon as you get it and continue to use it until the end. It may not seem like it reloads fast enough but overall it is the most efficient gun, scoring 1-2 kills per shot. P.S. won Jonestown on the first try...
 "Epic Battle Fantasy 3"){kind=icon}
 "The Last Stand 2"){kind=icon}