Here is the full list of all 25 Gimmick! Special Edition achievements.
True End achieved.
Unlocked all the achievements.
Stage 7 cleared.
Got the hidden item in stage 6.
Got the hidden item in stage 5.
Got the hidden item in stage 4.
Normal End achieved.
Stage 6 cleared.
I beat the wizard 'Ohagi'
I beat the wizard 'Ohagi2'
I defeated the soldiers guarding the castle.
Stage 5 cleared.
Stage 4 cleared.
Defeated the warrior Ohagi.
Stage 3 cleared.
I beat Ponta.
Got the hidden item in stage 3.
Stage 2 cleared.
Broke the 100000 SCORE
Got the hidden item in stage 2.
Broke the 60000 SCORE
Stage 1 cleared.
Broke the 30000 SCORE
Broke the 10000 SCORE
Got the hidden item in stage 1.