Here is the full list of all 19 GoNNER achievements.
There's nothing there! No easter egg, no extra item, no nothing. Just a dumb achievement.
Didn't have to skip death.
You became Death.
you found sally
You completed Death world! Woah!
Did you just run out of colors?
You hit the glyph cap!
I'm a serious adult person and I think this kind of humor is childish and should be banned.
I believe in you, get back up.
You jumped on 20 enemies in a row
You pushed that big piece of trash off your lawn. Good on you.
These combos are just getting ridiculous...
You completed Shooty world! Smooth!
You completed the Robot world. Impressive.
You got a combo of 15!
You completed the Cave world. Good job.
It's not even ASCII, how can it even be called Roguelike???
You got a combo of 5
You picked up a glyph!