So pretty long ago I played this game that piqued my interest.
It is pretty long since, but I want to at least know the name of the game. I tried for pretty long looking for games with the appropriate tags, but I can't find it :'(
It is a 2d single-player sidescroller game where you interact with different objects to go into different worlds. The main world is in an apartment building but there is only one corridor connected to a couple of rooms. And each of these rooms has an object you can interact with to go to these different worlds. The main gameplay is that you fight these creatures to get through the worlds, you don't level up, it is more about finding items to make you stronger. The game has a couple of horror elements and has jump scares. There is a couple of NPCs, the main one being your little sister. I also think there is a ghost running a train station that no one is using in the first world you find. At some point, you also open up the front door and you're able to buy from a shopkeeper outside. I don't think there is an ending to the game, at least there wasn't when I played through.