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.
Find the Tome artifact.
Find the Counting Cube artifact.
Get to the end.
Find the Writing Cube artifact.
Break the code.
Find your very first cube shard.
RTRTLTRTRTLTLTLT
Find an Anti-Cube.