These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
YMMV: The Lost Vikings
Crowning Music of Awesome: Lost Vikings 1 and 2 both have awesome, if somewhat limited, soundtracks. Norse By Norsewest has much more variety, but whether it's any better is very much a matter of preference.
Demonic Spiders: Cavemen and egyptians in the first game; wizards and gorillas in the second game. Cavemen and gorillas ball up and roll around making themselves invincible. Egyptians jumps aroung, easily bypassing Olaf's shield. Wizards constantly disappear, only rematerializing long enough for you to whack them, or, more likely, for them to nail you with a magic blast.
The rolling blades in the Factory World of the first game. They're the only enemy that can hurt Olaf through his shield.