Investigation missions are one of the big draws of the Secret world and quite a treat for anyone like me who loves a good puzzle and mystery. Not only that, but they are all sufficiently different from one another that you can’t solve them all the same way. While most use the Internet in some form, some will have you lookup references, another deduce code and another could be based on math or science.
Usually, each of these mission has a method to solve it that usually carry one through most of the mission. For example, if a mission is centered around Bible references, you can solve most of the mission by looking up Bible verses for example. The trick then to solve investigation quests is to figure out what is expected of you and that in itself is the biggest challenge.
Now this is the part where I get to admit that despite loving puzzles and giving them a lot of thought, I have cheated on at least one step of each investigation mission I have done save one. Most of them my cheating involved searching the web for how exactly does Funcom expects me to go about solving the puzzle. See, one of the hard part of puzzles is that sometimes you think it’s about finding out references about what an NPC just said when it fact that puzzle is about inventory manipulation. You can get stumped a very long time before figuring out you were searching in the wrong direction.
But yesterday, I finally managed to complete an entire investigation quest from start to finish without looking at any guide or cheating in any way and it felt incredible. I really need to do this more often because it was one of the most rewarding things I have ever done in an MMO, on par with server first kills and the like. I think Penny-Arcade captured the feeling better than I can with words.

It’s not TSW per say but the feeling still stands
It does feel amazing, doesn’t it? That’s why I can sometimes go for hours on the same investigation quest, and will only look things up if I am truly stumped with no other leads to go on.