I'm stuck in the house. It tells me to explore, and I think I did, since I went everywhere except the stairs. Someone help me.
Head to the end of the corridor and try to get into the basement to trigger the quest (you'll need a key). Then head over to the living room and open the door at the back (on the left side of your screen).
You'll find the key inside a cardboard box in that room, which will let you finally unlock that damn basement door.
If you want, there’s a walkthrough here that covers the first part of the game: here