Secrets:

Hard mode - Beat the game once

Unlockable Games -

Game: Busy Basket
How to Unlock: Beat Hard Mode

Game: Elf Chase
How to Unlock: Beat the game without making ANY chip recipes

Game: Hammer Harvest
How to Unlock: Beat the game in under 1 hour

Game: Magma Border
How to Unlock: Beat the game with a complete Database

Game: Plant Panic
How to Unlock: Beat the game while not feeding your cyber elf with energy crystals

Game: Wood Chopping
How to Unlock: Complete the game with an overall S-Rank

Game: Energy Lab.
How to Unlock: Beat the High Scores of all the above six Mini-Games

Unlock Ultimate Mode - beat the game with all 51 parts (have at least 1 of each part in your parts list) and have a fully upgraded cyber elf.