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.
Beat REMI with one hand
Play one hand mode with REMI
Beat MISAKO with one hand
Play one hand mode with MISAKO
Beat NIKITA with one hand
Play one hand mode with NIKITA
NEKOTINE naked
Beat NEKOTINE with one hand
Play one hand mode with NEKOTINE
Beat MOKOTO with one hand
Play one hand mode with MOKOTO
Beat YUMI with one hand
Play one hand mode with YUMI
YUMI naked
Beat TOMOKO with one hand
Play one hand mode with TOMOKO
TOMOKO naked
Beat ARISA with one hand
Play one hand mode with ARISA
ARISA naked
Beat MITSUMI with one hand
Play one hand mode with MITSUMI
MITSUMI naked
Beat SARAH with one hand
Play one hand mode with SARAH
REMI naked
Beat the PLAGUE boss
60% of clothes off REMI
30% of clothes off REMI
Play with all the girls
Unlock REMI TACHIBANA
MISAKO naked
60% of clothes off MISAKO
30% of clothes off MISAKO
NIKITA naked
60% of clothes off NIKITA
30% of clothes off NIKITA
30% of clothes off NEKOTINE
60% of clothes off NEKOTINE
Unlock NEKOTINE
MOKOTO naked
60% of clothes off MOKOTO
30% of clothes off MOKOTO
Beat the ARMORY boss
60% of clothes off ARISA
30% of clothes off ARISA
Unlock ARISA MIKEA
60% of clothes off YUMI
30% of clothes off YUMI
Gain 18 stars
Unlock NIKITA DORMER
Unlock MISAKO AOYAMA
Beat the SAMURAI boss
60% of clothes off TOMOKO
30% of clothes off TOMOKO
See the credits
Unlock YUMI MATSUDA
60% of clothes off MITSUMI
30% of clothes off MITSUMI
Unlock one hand mode
Unlock MITSUMI KATAGIRI
Date with a girl
Beat the VULCAN boss
SARAH naked
Gain 5 stars in one girl
60% of clothes off SARAH
30% of clothes off SARAH
Explode your first piece of clothes
Play the dating app