Kirby and the Forgotten Land has several secret codes hidden around the game that reward you with special loot. You can tell the Waddle Dee postman these codes in change for coins, Rare Stones, and other sweet stuff.
HOW TO CLAIM KIRBY AND THE FORGOTTEN LAND CODES:
After saving 50 Waddle Dees, a post office will open up in the Waddle Dee Town. Once it does, you can talk to the postman Waddle Dee to input codes. Some codes are baked straight into the game, but others are limited-time codes that you’ll need to connect to the internet to redeem.
Below is a list of all the currently available codes that you can claim without connecting to the internet:
BRAWLINGCOLOSSEUM (500 Star Coins, 1 Attack Boost)
CLEARDEMO (300 Star Coins)
FIRSTPASSWORD (100 Star Coins)
KIRBYSTORY (300 Star Coins)
KIRBYTHEGOURMET (1 Rare Stone, 1 Car-Mouth Cake)
NEWADVENTURE (300 Star Coins, 1 Rare Stone)
THANKYOUMETAKNIGHT (3 Rare Stones)
THANKYOUKIRBY (1,000 Star Coins, 1 Rare Stone)
Below are the codes that you need the internet to claim:
MOUTHFULMODE (100 Star Coins, 1 Car-Mouth Cake) EXPIRED
KIRBYNEWSDESK (150 Star Coins, 1 Energy Drink) EXPIRED
KIRBYMICROSITE (150 Star Coins, 1 Attack Boost)
KIRBYGAMESTOPCAN (150 Star Coins, 1 Maxim Tomato)
KIRBYADVENTURECALI (300 Star Coins, 4 food items) EXPIRED
GAMENEWS (1 Rare Stone)
ADVENTUREGUIDE (1 Rare Stone)
Not sure items
ICONELEMENTS (300 coins, 1 burger) (valid Apr 8 ~ May 6)
A few codes had already expired, I m still trying.