I had wondered why Durandal turned down godhood for a long time. I called it a Wall Banger, I called him too dumb to live, and more, but now I see the reason why. He doesn't want to be alone. Sure, he'd be a god, powerful enough to reshape his new universe, and able to do anything, but he would be alone. Also, he would know everything. He wants to know everything, but once he reaches that goal, he'd have no purpose. He would be lonely and unable to learn. That is a Fate Worse than Death.
In Infinity, the W'rkncacnter affects all the timelines. By preventing its release in one timeline, the player did it for all of them.
Infinity, such as the chapters after the Prologue being: Despair, Rage, and Envy, and the final level being Aye Mak Sicur.
The amount of detail that went into the plot sometimes is just staggering. Here (massive spoilers) is a good example of something that does not make the slightest bit of sense when you first play Infinity, but players have puzzled out what the developers were thinking when they developed the game and come up with explanations that make perfect sense. This is one of only dozens of examples, as well.
In Infinity and in Durandal we find out that the W'rkncacnter are not threatening when trapped in their prisons, however all of their prisons (blackholes, storms, stars, ect.) are temporary at best, meaning they would eventually get out, and having no way to kill them adds to the fear factor.
This one goes hand in hand with And I Must Scream. It turns out that Pathways Into Darkness and Marathon are in the same universe, and in that universe, when you die you are forever stuck in your body for the rest of eternity, or it is implied.
The cyborg tanks in the second and third games are confirmed by Word of God to be created from captured humans. When one thinks about the fact that the Pfhor are slavers and have thousands of years of history, one considers that they have probably done something similar to all of the races they've enslaved. There is also a theory that the "assimilated BoBs" - which look human, run up to you, and explode - might actually be captured humans as well, but the game says they're artificial constructs (however, whether this is actually the case is open to interpretation). Either way they're a pretty strong source of Fridge Horror as well.