Here is the full list of all 26 Nongunz: Doppelganger Edition achievements worth 1,000 gamerscore.
Nongunz
DCLXVI
XII
XX
XXIV
IX
100 \o/
V
I
50 \o/
:)
VI
:$
XVII
x100
:|
d_b
x50
x30
100000
10 \o/
III
:X
10000
x10
100