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