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