SureAI

Achieved when I was script killed by falling into digestive juice in that... worm... cave... thing. Whatever it was.

What achievement is this...? An achievement for dying? If so, it has no purpose since after dying you must reload, thereby losing the 'achievement' which is really just a faction rating.

But the curiosity is KILLING me - what IS the 'Agony' achievement...?

Hi.

I think that is just an "Easter egg" or very good sense of humour.
There is a list of possible achievements on German wiki and did not see "Agony" achievement anywhere. But I do remember having it myself when I burned up in some lava.

The Agony achievement is awarded for survival with a single hit point.
So in essence, you'll get it when you hit 1 hp.