Here is the full list of all 31 The Oil Blue: Steam Legacy Edition achievements.
Reclaimed an eighth island
Reclaimed a ninth island
Reclaimed a tenth island
Reclaimed an eleventh island
Reclaimed a twelfth island
Reclaimed a seventh island
Reclaimed a sixth island
Achieved Rank 5
Reclaimed a fifth island
Achieved Rank 12
Achieved Rank 10
Achieved Rank 9
Achieved Rank 8
Achieved Rank 7
Reclaimed a third island
Reclaimed a fourth island
Achieved Rank 22
Achieved Rank 18
Achieved Rank 15
Reclaimed a second island
Achieved Rank 36
Achieved Rank 32
Achieved Rank 28
Achieved Rank 25
Reclaimed your first island
Completed the tutorial
Achieved Rank 48
Achieved Rank 45
Achieved Rank 42
Achieved Rank 40
Booted up the Oil Blue Achievement App