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