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.
Find the Skull artifact.
Reactivate all 5 warp gates.
Get to the end.
Find the Tome artifact.
Find the Counting Cube artifact.
Find the Writing Cube artifact.
Find your very first cube shard.
Break the code.
Find an Anti-Cube.
RTRTLTRTRTLTLTLT