To unlock the Famished Feline achievement in The Medium, you'll need to make sure to feed Jack's cat before leaving the apartment to set out on your adventure.
While this is technically
missable, the fact that can be unlocked within a minute of starting a new playthrough means it won't cause you any headaches even if you don't get it on your first run. Which would be understandable — aside from this secret achievement, there's no reason to actually visit the kitchen in this opening sequence, after all.
Upon gaining control of Marianne, open the only door out of the starting room to reach the hallway. From here, the kitchen is the first room on the right, and that's where you'll find everything you'll need to pop this easy achievement... well, bar the cat itself, but it'll surely show up once you fill up its bowl.
To do so, make your way over to the counter and examine it to find exactly what you need — several tins of cat food. Grab one and head over to the door, where you should spot another interactive object down to the left of the doorway. This, as it turns out, is an empty cat bowl. Any guesses on how to solve this devious puzzle?
Simply interact with the bowl to bring up your inventory, then select the cat food — no, not the funeral parlour key or the tie clip — to fill it up. The little moggy will come running when it smells its dinner, and you'll find yourself 20G better off for taking the time to make sure your furry friend is fed.