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!
Get a gold rating on all optional levels
Earn a treasure score of 10000 on any level
Collect a treasure score of 6000 on the level Tomb of Osiris
Complete the fourth chapter
Get a gold rating on all chapter four story levels
Get a gold rating on all levels
Collect a total value of 250.000 in treasures
Get a gold rating on all chapter three story levels
Complete the third chapter
Get a gold rating on all chapter two story levels
Earn a treasure score of 8000 on any level
Get a gold rating on all chapter one story levels
Complete one of the optional levels
Complete the "Up, up and away" extra level in the Amazon Jungle
Defeat an Agent
Meet the Agent
Complete the second chapter
Defeat a Sentinel
Complete the first chapter
Defeat Exocet
Get a gold rating on 5 levels
Complete first puzzle