Here is the full list of all 12 FEZ achievements. It takes around 10-12 hours to unlock all of the achievements on Windows.
Find ALL collectibles.
Collect all 32 Golden Cubes and 32 Anti-Cubes.
Reactivate all 5 warp gates.
Find the Skull artifact.
Find the Tome artifact.
Find the Counting Cube artifact.
Get to the end.
RTRTLTRTRTLTLTLT
Break the code.
Find the Writing Cube artifact.
Find an Anti-Cube.
Find your very first cube shard.