Here is the full list of all 50 Adventure of Leek achievements.
Beat Lava Land III (Without Dying)
Beat The Game
Defeat Plum
Complete Speedrun Mode in less than 10 minutes
Beat Lava Land I (Without Dying)
Collect All The Coins (Worm Caves III)
Beat Lava Land III
Collect All The Coins (Lava Land III)
Beat Lava Land II (Without Dying)
Beat Lava Land II
Collect All The Coins (Lava Land II)
Beat Lava Land I
Collect All The Coins (Lava Land I)
Defeat 100 skull things
Look through the credits
Collect All The Coins (Worm Caves I)
Collect All The Coins (Canyons I)
Beat Worm Caves II (Without Dying)
Attempt Speedrun Mode
Defeat 10 skull things
Beat Worm Caves I (Without Dying)
Collect All The Coins (Canyons III)
Collect All The Coins (Canyons II)
Lose 100 Lives
Beat Worm Caves III (Without Dying)
Defeat The Serpent
Enter Lava Land
Beat Worm Caves III
Beat Worm Caves II
Collect All The Coins (Worm Caves II)
Defeat 100 worms
Beat Canyons III (Without Dying)
Beat Canyons II (Without Dying)
Beat Worm Caves I
Defeat 10 worms
Defeat The Moquito Brothers
Enter The Worm Caves
Beat Canyons III
Throw 1000 Water Balloons
Beat Canyons I (Without Dying)
Run out of Lives
Beat Canyons II
Defeat 100 snails
Beat Canyons I
Throw 100 Water Balloons
Lose 10 lives
Defeat 10 snails
Throw 10 Water Balloons
Lose 1 life
Enter The Canyons