It's rare for a FPS to entertain me so much. Loved it.
Also a theory...
Having played Portal 2 and Half-Life back to back, I get a feeling both G-Man, the blue gel from Portal 2, and maybe a bit of a stretch, but the floating isles of Xen, are all degrees of cosmic horrors.
Yet to play Half-Life 2 or Alyx to get a better idea, but G-Man having full control over portals seems quite strange, specially since before the ending, only the aliens of Xen appear using it willingly (although, as theirs are more limited than Aperture Science's, maybe they were studying it still, so not something they came up with).
In Portal 2, Cave Johnson mentions Aperture Science doesn't know what the blue gel is, only that it doesn't like human flesh. Besides the OSHA-posting style humor, sounds to me like a slight indication of cosmic horrors also.
And if Black Mesa indeed stole Aperture's technologies as Cave Johnson says, both would potentially be dealing with things way out of their control. And if G-Man indeed is a cosmic horror, he seems more rational than the usual depiction of such, and with his own agenda by what he says too. So since he has a discussion with a Black Mesa agent early in the game, maybe Black Mesa dealing with what would ultimately cause the invasion from Xen would be a problem to whatever he was after.
And the isles from Xen remind me of Eduardo Valdés-Hevia's flesh planet and Starbound's The Ruin, both shown as cosmic horrors.
