Here is the full list of all 31 Hidden Office achievements.
All levels completed
Snowshoe 2
Persian 2
Maine Coon 3
Striped Tabby 2
Tabby 3
Janese Bobtail 2
Janese Bobtail 1
Sphynx 1
Somali 1
Siamese 3
Tabby 2
Siamese 1
Somali 3
Russian Blue 3
Maine Coon 1
Sphynx 2
Maine Coon 2
Siamese 2
Persian 3
Snowshoe 3
Janese Bobtail 3
Russian Blue 2
Snowshoe 1
Striped Tabby 1
Sphynx 3
Striped Tabby 3
Somali 2
Russian Blue 1
Tabby 1
Persian 1