Look at the turquoise pot on the mantlepiece. Behind the left corner of the lid.
Look at the picture on the wall to the right of the mantlepiece. On the upper right is a roman II.
Look at the plant on the small table on the left. Behind the orange branches on the left.
Look at the legs of the small table on the left. The fourth bar from the right on the right set of bars.
Look at the yellow shade of the lamp on the ceiling. There are light grey dots on it. Click these.
Look at the blue shade of the lamp on the table in front of the window. There’s a 6 on it but that’s not the one. On the chair on the left, under the (viewers) left arm is a little corner of the correct one… eeehhh six.
Look at the top row of yellow dots in front of the window. In the right corner of the upper left window pane is a light green stripe.
Look at the grey base of the lamp on the round table in front of the yellow dots. On the green shade is a light grey square.
Look at the books under the table in the front.
Look at the seat of the chair on the far right. The pixel is on the red tapestry.
Game source: A copy of the game was found here on the internet.