I vividly remember playing a cat care game somewhere between 2012-2015.
It was very minimalistic. The game had a simple, pixelated art style, utilising mostly muted, realistic colours. It didn't have black, clear outlines, rather soft shading around the edges. The game had a very slow pace. It also had a fixed angle and the cats were quite small, just lumps of pixels without a face.
The room the cats were in had a red carpet and a yellowish wall. There was a litter box in said room, in which the cats would poop and you'd have to clean it up. I remember this detail because I, being a child that was barely aware of its own existence at the time, found it fascinating that a video game would show feces (even if it wasn't graphic).
The cats would die if you neglected them. Once they were dead, their body would lay limp in the living room and you'd have to clean it up. This part really scared me, because their death was very realistic to me. I don't remember if the game had any music at all, but if it did, it'd go quiet when a cat died.
I also don't remember how one would obtain cats, but I do remember it was complicated for me back then, so I stopped playing.
I've played it on Android, if that's any help.