If you happen to pick up the artifact "Ragnarok", then get a holy grail of Jure (or 2), and a good weapon. If you can kill the dragons that spawn, you get a hell lotta exp (depending on your lv). I'd suggest using a laser pistol, gravity gun, or a piercing bowgun.
The power-ups the zombies drop resemble WaW Nazi's Zombie's power-ups.
X2 Damage - Insta-kill
X2 Cash - Double Points
Max Ammo - Max Ammo
Super-bomb - Nuke
If you look at the "Hurt me Plenty" perk, it has the same picture of the "Bloody Mess" perk from Fallout 3, except replaced with the game's characters.
This game has alot of things that remind me of Fallout 3. For example, some perks are the same from Fallout 3 (The "Hurt me Plenty" perk is Bloody Mess).