Here is the full list of all 25 Legend of Kay - there are Anniversary achievements worth 1,000 gamerscore.
Complete the first sword training
Win the first fight against Boarax
Complete the second fight training lesson
Finish the first boar race
Get a 5x Combo
Get a 10x Combo
Get a 15x Combo
Get a 20x Combo
Upgrade your extra-lives to 9
Win the fight against Jia-Gu
Win the fight against Shun's Bodyguard
Win the fight against Qian Bei
Win the fight against The Dreaded Chei Ni
Win the fight against Alchemist Tak, King of the Rats
Finish the game on „Hard“ difficulty
Upgrade your Health Points to the maximum
Upgrade your Chi Points to the maximum.
Collect all the three different armour types.
Collect all Claws in the game
Collect all hammers in the game
Win an extra race without collecting a chilli
Collect all Swords in the game
Find and activate all demon portals
Finish the game on „Nightmare“ difficulty.
Win the fight against Minister Shun, Lord of the Gorillas