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.
Did you just run out of colors?
you found sally
I believe in you, get back up.
I'm a serious adult person and I think this kind of humor is childish and should be banned.
You pushed that big piece of trash off your lawn. Good on you.
It's not even ASCII, how can it even be called Roguelike???
You became Death.
Didn't have to skip death.
You completed Death world! Woah!
These combos are just getting ridiculous...
You completed Shooty world! Smooth!
You completed the Robot world. Impressive.
You hit the glyph cap!
You completed the Cave world. Good job.
You jumped on 20 enemies in a row
You got a combo of 15!
You picked up a glyph!
You got a combo of 5