Remember your high school friend who always took the joke a little too far? The one who thought South Park was the height of satire and had no ability to read between the lines? The one who thought the only funny jokes were dead baby jokes?
Agony is what would happen if that kid played 2016's DOOM and decided he needed to make his own version of it. Even if the repetitive gameplay, terrible save system, and clunky stealth mechanics were fun, you're still left with a game that seems to believe that the only way to be frightening is to disgust and sicken. It's horror without mystery, fear without the fun, and disgust without the meaning. It's a 100,000 word novel, but it's just the same word written over and over again.
That word is probably "agony", by the way.
(Editor's Note: this final joke has been put here by the recent law stating that a game review about Agony must contain some variation of said joke.)