Here is the full list of all 26 Hamilton's Great Adventure achievements.
Complete Dungeon #9
Get a gold rating on all Retro Fever levels
Complete Some heads are gonna roll
Complete It’s a me, Hamilton!
Complete the fourth chapter
Get a gold rating on all chapter four story levels
Get a gold rating on all levels
Get a gold rating on all optional levels
Collect a treasure score of 6000 on the level Tomb of Osiris
Complete the third chapter
Get a gold rating on all chapter three story levels
Collect a total value of 250.000 in treasures
Get a gold rating on all chapter two story levels
Earn a treasure score of 10000 on any level
Complete the second chapter
Earn a treasure score of 8000 on any level
Defeat a Sentinel
Defeat an Agent
Meet the Agent
Complete one of the optional levels
Complete the "Up, up and away" extra level in the Amazon Jungle
Complete the first chapter
Get a gold rating on all chapter one story levels
Defeat Exocet
Get a gold rating on 5 levels
Complete first puzzle