Here is the full list of all 489 NGHTMN achievements. It takes around 0-1 hour to unlock all of the achievements on Windows.
BLADE
PANDA
SKILLET
EYE
CAT
HELM
BAT-SWORD
AXE
AQUA
SATANA
ZIPZAP
ARROWS
ATOM
SWORDS
ANCHOR
ANIMAL
CARD
ALIEN
ELF
DWARF
ARROW
GUN
PICE
NINJA
ORE
NAUTILUS
CHICKEN
LVL UP
DRAGON
OLYMP
CHILLI
STRONG
SKULL
BEAR
MONEY
SHILD
ANARHIY
BAT
BANAN
Eye of Providence
FARAON
EXPAND
CONTRACT
KING
RA
FIRE
SPIDER
V
W
X
Y
Z
U
S
T
Q
R
P
С
Е
M
N
O
K
L
G
I
J
H
D
E
F
A
B
C