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.
That One Level: Level 2 in Turok 2: Seeds of Evilwas this for Tom, to the point of going to Levels 3 and even 5 first. Then he went to Level 4 and realized Level 2 really wasn't that bad by comparison.
For Charles, it's Episode 4 of Quake, due to Spawns and the episode not caughing up a rocket launcher until the second-to-last level.