I hope you don't mind me spotting some errors. This is a quick painting you did but for further development of the painting you could consider these,
The two wooden planks(?) above our head explain the perspectives and I am not sure if it is going outside the building. If it isn't going outside the building, judging by the amount of light it receives, the whole room should be brightened up a little bit more (since more light is coming in, i hope you got the point) , give the objects in the foreground more silhouette feel.
Answering to the tetris question. Its not just tetris, you can make it as a BG, something that is not really lived by humans or little fighters. We don't live inside clocks, you could make a seconds hand sweep in the BG. They are little fighters, so place them in small place . Just being craaazy. :P
The two wooden planks(?) above our head explain the perspectives and I am not sure if it is going outside the building. If it isn't going outside the building, judging by the amount of light it receives, the whole room should be brightened up a little bit more (since more light is coming in, i hope you got the point) , give the objects in the foreground more silhouette feel.
Answering to the tetris question. Its not just tetris, you can make it as a BG, something that is not really lived by humans or little fighters. We don't live inside clocks, you could make a seconds hand sweep in the BG. They are little fighters, so place them in small place . Just being craaazy. :P