Here is the full list of all 16 Keen Dreams achievements.
Get the maximum possible score on Horseradish Hill
Get the maximum possible score in the Melon Mines
Get the maximum possible score at Bridge Bottoms
Get the maximum possible score at Parsnip Pass
Get the maximum possible score in Spud City
Complete Apple Acres with the highest possible score.
Complete Grape Grove with the highest possible score.
Compete Brussel Sprouts Bay with the highest possible score.
Complete Squash Swamp with the highest possible score.
Complete Castle Tuberia with the highest possible score
Collect all 24 Boobus Bombs
Complete an entire game in CGA mode.
Complete the game on "Easy" difficulty.
Complete the game on "Normal" difficulty.
Complete the game on "Hard" difficulty.