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