Here is the full list of all 69 DEEP SPACE WAIFU achievements. It takes around 1-2 hours to unlock all of the achievements on Windows.
Play with all the girls
Unlock NEKOTINE
Unlock REMI TACHIBANA
Unlock ARISA MIKEA
Unlock MISAKO AOYAMA
60% of clothes off MITSUMI
30% of clothes off MITSUMI
Unlock NIKITA DORMER
MOKOTO naked
60% of clothes off MOKOTO
30% of clothes off MOKOTO
Unlock YUMI MATSUDA
Beat the VULCAN boss
SARAH naked
60% of clothes off SARAH
30% of clothes off SARAH
Unlock MITSUMI KATAGIRI
Date with a girl
Beat the SAMURAI boss
Gain 5 stars in one girl
60% of clothes off TOMOKO
30% of clothes off TOMOKO
Explode your first piece of clothes
Play the dating app
See the credits
Beat the ARMORY boss
Beat the PLAGUE boss
TOMOKO naked
Play one hand mode with TOMOKO
Beat TOMOKO with one hand
Play one hand mode with SARAH
Beat SARAH with one hand
Play one hand mode with MOKOTO
Beat MOKOTO with one hand
MITSUMI naked
Play one hand mode with MITSUMI
Beat MITSUMI with one hand
30% of clothes off NIKITA
60% of clothes off NIKITA
NIKITA naked
Play one hand mode with NIKITA
Beat NIKITA with one hand
30% of clothes off YUMI
30% of clothes off MISAKO
60% of clothes off YUMI
MISAKO naked
YUMI naked
Play one hand mode with YUMI
Play one hand mode with MISAKO
Beat YUMI with one hand
Beat MISAKO with one hand
30% of clothes off ARISA
60% of clothes off ARISA
ARISA naked
Play one hand mode with ARISA
Beat ARISA with one hand
30% of clothes off NEKOTINE
60% of clothes off NEKOTINE
NEKOTINE naked
Play one hand mode with NEKOTINE
Beat NEKOTINE with one hand
30% of clothes off REMI
60% of clothes off REMI
REMI naked
Play one hand mode with REMI
Beat REMI with one hand
Unlock one hand mode
Gain 18 stars
60% of clothes off MISAKO