Here is the full list of all 69 Deep Space Waifu: FLAT JUSTICE achievements. It takes around 2-3 hours to unlock all of the achievements on Windows.
Complete ONE HANDED SHARP-EYE
Defeat the Fake Wadding
complete ONE HANDED SPY
Complete ONE HAND LIME CODE
Complete ONE HAND SERGEANT CHIKARA
Complete ONE HAND PUCKY K-9 UNIT
Complete ONE HANDED MILF
Complete ONE HAND NORMAL ROCKY CHAN
Complete ONE HAND JULIA
Use the JUSTICE LASER special attack
Finish with the M.I.L.F.
Defeat Dickus final form
100% M.I.L.F.
Infiltrate in the secret TENTACLE organization
Destroy the Sneak Mothership
complete 100% the spy
Defeat DP Miner
100% SERGEANT CHIKARA
Get the super scret spy business card
Defeat Dickus third form
100% LIME CODE
Be spotted by the enemy
Complete NORMAL ROCKY-CHAN
Defeat the Thrasher Super Mecha Warrior
Unlock LIME CODE
Get the F.L.A.T. Multipass badge
Reach 30 STARS
Defeat Dickus second form
100% PUCKY K-9 UNIT
Complete ONE HAND METAL ROCKY CHAN
100% METAL ROCKY CHAN
Complete an ONE HANDED SALE
100% SHARP-EYE YUMIKO
Complete ONE HAND NAO
Complete ONE HAND MIKA
Get promoted to the F.L.A.T. SPECIAL FORCES
Get a smelling Pantie evidence
Reach 18 STARS
Complete SAYRU-CHAN
Defeat DP Mothership
Get a special Phone Number
Reach 10 STARS
100% JULIA SUZUHARA
Defeat Dickus first form
Make a 5 STARS stage
DATE all girls
Unlock SAYRU-CHAN
Unlock SHARP-EYE YUMIKO
Unlock METAL ROCKY-CHAN
Unlock NORMAL ROCKY-CHAN
Unlock PUCKY K-9 UNIT
Unlock SERGEANT CHIKARA
Unlock M.I.L.F.
Find the PERFECT FLATNESS
Unlock the SECRET SPY
Defeat DP Defender
100% NAO NEKOYAMA
Get the MACHINE GUN power up
Get the RAY power up
Get the SHIELD power up
Explode a mine!
Take a photo of a girl
Kick Justice in the balls
100% MIKA MOKOTO
Get the LASER power up
Get the ROCKET LAUNCHER power up
Torn apart your first piece of cloth
Go to your first date
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