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